Skepticism and critical thinking is not panacea, but can help to understand the world better
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May the source be with you, but remember the KISS principle ;-) Skepticism and critical thinking is not panacea, but can help to understand the world better |
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Tar is a very old (dates back to Version 6 of AT&T UNIX, circa 1975) zero-compression archiver. But it is not easy to replace it with any archiver that has a zero-compression option (for example zip) as with time it got some unique capabilities and became a standard de-facto for zero compression archiver.
Unlike most archivers, tar can be used as the head or tail of a pipeline. tar is very convenient for moving hierarchies directories hierarchies while preserving all attributes and symbolic and hard links between servers.
Archive created by tar is usually called tarball. A tarball historically was a magnetic tape, but now it's usually a disk file. The default device, /dev/rmt0, is seldom used today, the most common is to archive into file that is often processed additionally by gzip, or, for text files, xz (option -J).
The tar command can specify a list of files or directories and can include name substitution characters. The basic form is
tar keystring options -f tarball filenames... .
The keystring is a string of characters starting with one function letter (c, r, t , u, or x) and zero or more function modifiers (letters or digits), depending on the function letter used. tarball is specified after option -f. Omitting -f us the most common mistake for novice users of tar.
You can specify keysting values as options too because previous version of tar did not havethe idea of keystring and this was prevered for compatibility.
tar options files_to_include
You can perform several standard for archivers operations on tarball. In this sense tar is just another member of the family. Among typical operations:
We will discuss GNU tar implementation. There is alternative implementation called star that many prefer, but GNU tar is standard in commercial Linux distributions and is available for all other flavors of Unix so we prefer it. GNU tar has several interesting additional features such as:
tar cvf myarchive.tar -X exclude.lst -T include.lst
Tar is often used along with gzip and bzip2. Not all tar implementations are created equal. In the past Solaris tar understand ACLs but later GNU tag caught up and now is the best implementation.
The current version of tar as of August 2012 is 1.26 (dated 2011-03-13). Versions used differ in different linux distributions:
While being just a zero compression archiver, tar has several capabilities that regular archivers usually do not have and as such it is very convenient for many tasks like backups and replication of filesystem from one server to another.
File limits are different for various OSes. Older Unixes often used to have 2G file limit. Obviously, older tar programs also won't be able to handle files or archives that are larger than 2^31-1 bytes (2.1 Gigabytes). Try running 'tar --version'. If the first line indicates you are using gnu tar, then any version newer than 1.12.64 is able to work with large files. You can also try command:
strings `which tar` | grep 64
you should see some lines saying lseek64, creat64, fopen64. If yes, your tar contains support for large files. GNU tar docs also mention that the official POSIX tar spec limits files to 8GB, but that gnu tar will generate non-POSIX (therefore possible non-portable files) with sizes up to something like 2^88 bytes. Still formally tarballs that you want to use on any other POSIX computer are limited to 8GB files.
Since the majority of tarballs are gzip'ed, the maximum filesize may be limited to due to gzip limitation. The newer versions of gzip (1.3.5 and above) support large files. Before that the limit was 2GB. To check gzip version use
gzip --version
Unlike many other utilities tar does not assume that the thirst argument is the tar archive to operate with. Tar assumes that the first argument is a file to operate with. This created problems in novices. For example, unlike most Unix and DOS utilities, listing of the tar archive requires two options t and f (file to be listed).
tar tf myfiles.tar tar tvf myfiles.tar
See also Google Answers UNIX Question! tar size constraint.
The limit for the length of file names is around 256, but can be as low as 100 on older Oses.
Note:
In old versions of tar because of limitations on header block space in the tar command, user numbers (UIDs), and group identification numbers (GIDs) larger than 65,535 will be corrupted when restored by GNU tar.
Tar is one of the few backup programs that is pipable.
The functions supported by tar are the same as for any archiver:
Note: you need to specify option -f, if you want to list a content of tarball.
Information can be listed about all files or a given set of files. If no file argument is given, the list of names of all files in the tarball are listed. With the option -v , additional information for the specified files is displayed. For example:
tar -tf etc_baseline110315_0900.tar tar -tf etc_baseline110315_0900.tar hosts
tar xfz filename.tar.gz -C PathToDirectory
The command extracting the tar contents into particular directory …
The most popular options include:
Three examples:
Main options:
You need to use option c - Create which imply that the writing begins at the beginning of the tarball, instead of at the end. The tar command for creating a tar archive uses a string of options as well as a list of what files are to be included and names the device to be written to. The default device, /dev/rmt0, is seldom used today, the most common is to archive into file that is often processed additionally by gzip
tar cvf myarchive.tar *
The cvf argument string specifies that you are writing files (c for create), providing feedback to the user (v for verbose), and specifying the device rather than using the default (f for file). You can instantly pipe tar archive into gzip by specifying z option:
tar cvzf myarchive.tgz *
The convention is to extension tar for tar archive and tgz for tared and gziped archives. Please note that tgz archives are monolithic bricks and are just designed to store files. But with regular tarball you can do several operations. In the past instead of gzip, the standard compress utility was used In this case archives have prefix tar.Z.
To create an archive, you use the command.
tar -cvf archivename.tar directory_or_list_of_files_or_regular_expression
Always use option -v to see what is happening. To put files in an archive, you need at least read permissions to the file. For example to compress your home directory and pup the resulting archive in /tmp you can use the command
tar -cvf /tmp/joeuser.tar /home/joeuser
Notice the options that are used; the order in these options is important -- the last one should be option f which
specifies where to pur the archive we are creating
Similarly you can create archive of etc
tar -cvf /root/etc181006.tar /etc
Originally, tar did not use the dash (-) in front of its options. Modern tar implementations use that dash, as do all other Linux programs, but they still allow the old usage without a dash for backward compatibility.
While managing archives with tar, it is also possible to add a file to an existing archive, or to update an archive. To add a file to an archive, you use the -r options. For example:
tar -rvf /root/etc181006.tar /root/*cfg /root/.bash*
To update a currently existing archive file, you can use the -u option:
tar -uvf /root/etc181006.tar /root/*cfg /root/.bash*
write newer versions of specified files all files in /home to the end of archive and correct the directory of the archive to to new entroies. Older files are not deleted so archive increases in size.
Archive of /etc and home directory usually are compresses with gzip achieving approximately 300% compression (the compressed file is one third of the size of the directory).
# mkdir /root/Archive # tar -cv /etc | gzip > /root/Archive/etc`date +"%y%m%d"`.tgz # du -sh /etc 30M /etc # ll /root/Archive total 9568 -rw-r--r--. 1 root root 9795626 Oct 7 17:47 etc181007.tgz
Binary files also can be compressed at least to 50% of the original size. So you can save tremendous amount of space used for storing those archive (and typically archives are stored for a couple of years in enterprise environment).
You can compress tarball after it can was created on on the fly.
Compression after it was created is typically done via pipe. this make sense to do only for parallel version of compressors as regular version can be invoked via tar option:
tar -cv /etc | bzip2 > /root/etc181006.tar.bgz
on /etc directory bzip2 provides ~12% better compression then gzip, while xz provides ~30% better compression. So you save one archive space each ten days if you do it daily from cron. For very large archives (say over 500M) is makes sense to use only parallel version of compressions -- pigz and bzip2. Especially the last, as it provides better compression ration, while maining adequate (although slightly slower then pigz) speed.
On the fly compression is specified via one of tar option -z for gzip, -j for bzip and -J for xz. For example
tar -cvzf /root/etc181006.tgz /etc
To decompress files that have been compressed with gzip or bzip2, you can use the gunzip and bunzip2 utilities. Decompression speed is approximately the same for all three compression programs we discussed.
Here are compressed sizes of default content of /etc directory in RHEL 7 using those three compression programs:
[root@test01 Archive]# ll total 24600 -rw-r--r--. 1 root root 8580949 Oct 7 17:56 etc181006.tbz -rw-r--r--. 1 root root 9795626 Oct 7 17:47 etc181006.tgz -rw-r--r--. 1 root root 6808940 Oct 7 18:04 etc181006.txz
For large directories of files it does not make any sense to use built-in option and you are better off compressing the tarball via pipe using parallel version of archivers. for xz it makes sense to do it in all cases as non-parallel version in excruciatingly slow even on /etc directory.
There is no need to specify these options while extracting. The tar utility recognizes the type of compressed contents and automatically decompress it.
To list the contents of a tar file without extracting, use the t option as shown below. Including the v option as well results in a long listing.
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You need also specify option -f to list the files in the tarball. The most common problem that novices experience with the option -v is forgetting about the necessity to use also option -f to specify the file |
TIP: As most people forget to specify option f to list the file it is better to create alias, for example
alias tls='tar -tf'
and put it in your .bash_profile file
This is one of tar idiosyncrasies and source of a lot of grief for system administrators, who type tar -t myfiles.tar and receive nothing as tar tries to read standard input.
tar tf myfiles.tar tar tvf myfiles.tar
To extract to standard output a file from archive you can use -O or --to-stdout, for example
tar -xOf myfiles.tar hosts | moreHowever, --to-command may be more convenient for use with multiple files.
Archives created with tar include the file ownership, file permissions, and access and creation dates of the files. The p (preserve) option restores file permissions to the original state. This is usually good since you'll ordinarily want to preserve permissions as well as dates so that executables will execute and you can determine how old they are. In some situations, you might not like that original owners are retrieved, since the original owners may be people at some other organization altogether. The tar command will set up ownership according to the numeric UID of the original owner. If someone in your local passwd file or network information service has the same UID, that person will become the owner; otherwise the owner will display numerically. Obviously, ownership can be altered later.
tar xvpf myachive.tar
Extract each file from a shell prompt by typing tar xvzf file.tar.gz from the directory you saved the file.
I would like to remind you again that you can also extract individual file to standard output (via option -O) and redirect it, for example
tar -xvOf /root/etc_baseline110628_0900.tar hosts > /etc/hosts110628
One of the rarely mentioned capabilities of tar is its ability to serve as diff for between the directory and the tarball
The command is (assuming the root was the current directory when tarball was created
cd /etc && tar -df /tmp/etc20141020.tar 2>dev/nullUnfortunately if some files are missing from the directory this comparison operation fails to produce different files. In some cases tar just lists missing files but not differing files. This looks like a bug in current version
From tar manual
4.2.6 Comparing Archive Members with the File System
The `--compare' (`-d'), or `--diff' operation compares specified archive members against files with the same names, and then reports differences in file size, mode, owner, modification date and contents. You should only specify archive member names, not file names. If you do not name any members, then
tarwill compare the entire archive. If a file is represented in the archive but does not exist in the file system,tarreports a difference.You have to specify the record size of the archive when modifying an archive with a non-default record size.
tarignores files in the file system that do not have corresponding members in the archive.The following example compares the archive members `rock', `blues' and `funk' in the archive `bluesrock.tar' with files of the same name in the file system. (Note that there is no file, `funk';
tarwill report an error message.)$ tar --compare --file=bluesrock.tar rock blues funk rock blues tar: funk not found in archiveThe spirit behind the `--compare' (`--diff', `-d') option is to check whether the archive represents the current state of files on disk, more than validating the integrity of the archive media. For this latter goal, see Verifying Data as It is Stored.
diff a gzipped tarball against a directory
user394
Is there a way I can diff a gzipped tarball against an existing directory?
I would like to be able to do it without extracting the data from the tarball.
Mount the tarball as a directory, for example with AVFS. Then use
diff -r on the real directory and the point where the tarball is mounted.
mountavfs
diff -r ~/.avfs/path/to/foo.tar.gz\# real-directory
Turns out that GNU tar has diff built in (-d):
$ #Create the archive and a difference:
$ echo one>file1;echo two>file2;tar -czf archive.tgz file*;echo changing>>file1
$ tar -dzf archive.tgz
file1: Size differsIf you are working with tar that does not have this try:
$ for F in `tar -tzf archive.tgz`;do tar -xzOf archive.tgz $F|diff --brief - $F;done
Files - and file1 It also has very useful but rarely used and poorly understood feature called tag files. Any directory tagged with such a file is automatically excluded.
The simplest way to avoid operating on files whose names match a particular pattern is to use `--exclude'
tar to ignore files that match the pattern. Forward slash is OK if you use it with the option, for example
--exclude=/proc -- exclude=/sys
The `--exclude=pattern' option prevents any file or member whose name matches the shell wildcard (pattern) from being operated on. For example, to create an archive with all the contents of the directory `src' except for files whose names end in `.o', use the command
tar -cf src.tar --exclude='*.o' src
You may give multiple `--exclude' options.
tar to ignore files that match the patterns listed in file. The tar command also enables you to create lists of files that should be excluded from into tarball. The option -X accomplish that and it can be used with the option -T (include files from the list, see below) .
For example
ls *.zip > exclude.lst tar cvf myarchive.tar -X exclude.lst *
in this case zip files will not be included into the archive. It's a good idea to exclude the exclude file itself, as well as the tar file that you are creating in your exclude file. Notice that this has been done in the following example:
tar cvf myarchive.tar -X exclude.lst *
When archiving directories that are under some version control system (VCS), it is often convenient to read exclusion patterns from this VCS' ignore files (e.g. `.cvsignore', `.gitignore', etc.) The following options provide such possibility:
The patterns are treated much as the corresponding VCS would treat them, i.e.:
Any line beginning with a `#' is a comment. Backslash escapes the comment character.
Any line beginning with a `#' is a comment.
tar checks if it contains file. If so, exclusion patterns are read from this
file. The patterns affect only the directory itself. As of version 1.29, the following files are excluded:
When creating an archive, the `--exclude-caches' option family causes tar to exclude all directories
that contain a cache directory tag. A cache directory tag is a short file with the well-known name `CACHEDIR.TAG'
and having a standard header specified in http://www.brynosaurus.com/cachedir/spec.html.
Various applications write cache directory tags into directories they use to hold regenerable, non-precious data, so that such data
can be more easily excluded from backups.
There are three `exclude-caches' options, each providing a different exclusion semantics:
tar has the ability to ignore specified files and directories contained in a special file. The localtion of the file
is specified with option -X or `--exclude-from'
The syntax is one definition per line. Each line is interpreted as a basic regular expression (tar documentation stupidly call this "pattern")
Thus if tar is called as `tar -c -X foo .' and the file `foo'
contains a single line `*.o', no files whose names end in `.o' will be added to the archive.
Notice, that lines from file are read verbatim. One of the frequent errors is leaving some extra whitespace after a file name, which is difficult to catch using text editors.
However, empty lines are OK and are ignored. They can be used for readability.
For example:
# Not old backups
/opt/backup/arch-full*
# Not temporary files
/tmp/
# Not the cache for pacman
/var/cache/pacman/pkg/
see BackupYourSystem-TAR - Community Help Wiki
Another option family, `--exclude-tag', provides a generalization of this concept. It takes a single argument, a file name to look for. Any directory that contains this file will be excluded from the dump. Similarly to `exclude-caches', there are three options in this option family:
Multiple `--exclude-tag*' options can be given.
For example, given this directory:
$ find dir dir dir/blues dir/jazz dir/folk dir/folk/tagfile dir/folk/sanjuan dir/folk/trote
The `--exclude-tag' will produce the following:
$ tar -cf archive.tar --exclude-tag=tagfile -v dir dir/ dir/blues dir/jazz dir/folk/ tar: dir/folk/: contains a cache directory tag tagfile; contents not dumped dir/folk/tagfile
Both the `dir/folk' directory and its tagfile are preserved in the archive, however the rest of files in this directory are not.
Now, using the `--exclude-tag-under' option will exclude `tagfile' from the dump, while still preserving the directory itself, as shown in this example:
$ tar -cf archive.tar --exclude-tag-under=tagfile -v dir dir/ dir/blues dir/jazz dir/folk/ ./tar: dir/folk/: contains a cache directory tag tagfile; contents not dumped
Finally, using `--exclude-tag-all' omits the `dir/folk' directory entirely:
$ tar -cf archive.tar --exclude-tag-all=tagfile -v dir dir/ dir/blues dir/jazz ./tar: dir/folk/: contains a cache directory tag tagfile; directory not dumped
From: Problems with Using the exclude
Options
Some users find `exclude' options confusing. Here are some common pitfalls:
tar does not act on a file name explicitly listed on the command line, if one of its
file name components is excluded. In the example above, if you create an archive and exclude files that end with `*.o',
but explicitly name the file `dir.o/foo' after all the options have been listed, `dir.o/foo' will be
excluded from the archive. tar sees wildcard characters like `*'. If you do not do this, the shell might expand the `*'
itself using files at hand, so tar might receive a list of files instead of one pattern, or none at all, making the
command somewhat illegal. This might not correspond to what you want.
For example, write:
$ tar -c -f archive.tar --exclude '*.o' directory
rather than:
# Wrong!
$ tar -c -f archive.tar --exclude *.o directory
regexp syntax, when using exclude options in tar.
If you try to use regexp syntax to describe files to be excluded, your command might fail. In earlier versions of tar, what is now the `--exclude-from' option was called `--exclude'
instead. Now, `--exclude' applies to patterns listed on the command line and `--exclude-from' applies
to patterns listed in a file.
The include file can be used to specify which files should be included.
Combining tar with the find utility, you can archive files based on many criteria, including such things as how old the files are, how big, and how recently used. The following sequence of commands locates files that are newer than a particular file and creates an include file of files to be backed up.
find -newer lastproject -print >> include.lst tar cvf myfiles.tar -T include,lst
That is especially important if you bring archive to a new place after modifying some files in the morning and need to merge changes back in the evening.
Both an include and an exclude file are used. Any file that appears in both files, by the way, will be included.
tar cvf myarchive.tar -X exclude.lst -T include.lst
Notice how we use options that require parameters: the first such option is used as the last in in the first string of options (cvf) and then each option specified separately with its parameter.
GNU tar has some features that enable it to mimic the behavior of find and tar in a single command.
Tar archives can be transferred with remote copy commands such as ssh, scp, ftp, kermit, etc. These utilities know how to deal with binary data. To mail a tarball, you need first encode the file to make it work. The uuencode command turns the contents of files into printable characters using a fixed-width format that allows them to be mailed and subsequently decoded easily. The resultant file will be larger than the file before uuencoding; after all, uuencode must map a larger character set of printable and nonprintable characters to a smaller one of printable characters, so it uses extra bits to do this, and the file will be about a third larger than the original.
mv command could not be used to move directories across file systems. A file system can be thought of as a hard drive or hard drive partition. The mv command works fine when you want to move a directory between different locations on the same file system (hard drive), but it doesn't work well when you want to move a file across file systems. Depending on your version of mv, an error message could be generated when you try to do this.
For example, consider this directory:
ls -F /tmp/ch2 ch2-01.doc ch2.doc@
If you use the mv command to move this directory in the directory /home/mybook on a different file system, an error message similar to the following is generated:
mv: cannot move 'ch22' across filesystems: Not a regular file
Some UNIX versions implement a workaround inside mv that executes the following commands:
rm -rf destination cp -rPp source destination rm -rf source
Here source and destination are directories.
The main problem with this strategy is while symbolic links are copied, hard links in the source directory are not always copied correctly. Sometime coping hard links is just impossible as target of the move operation can be in a different filesystem.
In addition to this, there are two other minor problems with using cp:
The workaround for these problems is to use the tar ( tar as in tape archive ) command to copy directories. This is usually accomplished with pipe and such an operation became a Unix idiom for copying large tree of file, possibly the whole filesystem:
(cd mydata; tar cvf - *) | tar xpBf -
What this command does is move to a subdirectory and read files, which it then pipes to an extract at the current working directory. The parentheses group the cd and tar commands so that you can be working in two directories at the same time. The two - characters in this command represent standard output and standard input, informing the respective tar commands where to write and read data. The - designator thereby allows tar commands to be chained in this way.
You can also use cd command with the target directory instead of source directory. For example:tar cvz joeuser | (cd /Archive && tar xpz )
You can also move file from one server to another. See Cross network copy
Archives created with tar preserve the file ownership, file permissions, and access and creation dates of the files. Once the files are extracted from a tar file they look the same in content and description as they did when archived. The p (preserve) option will restore file permissions to the original state. This is usually a good idea since you'll ordinarily want to preserve permissions as well as dates so that executables will execute and you can determine how old they are.
In some situations, you might not like that original owners are restored, since the original owners may be people at some other organization altogether. The tar command will set up ownership according to the numeric UID of the original owner. If someone in your local /etc/passwd file or network information service has the same UID, that person will become the owner; otherwise the owner will display numerically. Obviously, ownership can be altered later. But in this case you may want to unpack the archive as a regular user instead of root. If you unpack this archive with other user privileges (non-root) all uid and gid will be replaced with the uid and gid from this user.
Keep that in mind, if you make backups/restore, practically always you need to do it using UID 0 (root).
No tar tutorial is complete without an example of a cross-network copy. This is often called tar-to-tar file transfere. One tar command creates an archive with one tar command while the other extracts from the archive without ever creating a *.tar file. The only problem with this command is that it looks a bit awkward. This capability depends of present of ssh or rsh.
To copy a directory hierarchy using this technique, first position yourself in the source directory:
cd fromdir
Next, tar the contents of the directory using the create (i.e., the "c" Option). Pipe the output to a tar extract (i.e., the "x" option) command. The tar extract should be enclosed in parentheses and contain two parts:
| if you are not sure how tar archive was created it is safer to expand it first in /tmp and see results before restoring it to the original tree (especially if this is a system directory). |
For example:
tar cBf - * | (cd todir; tar xvpBf -)
The hyphens in the tar command inform tar that no file is involved in the operation. The option B forces multiple reads and allows the command, as needed, to work across a network. The "p" is the preserve option - generally the default when the superuser uses this command.
Using tar-to-tar commands across you can move tree of directories from one server to another with a single command:
cd /home/joeuser tar cBf - *" | ssh new_server "cd /home/joeuser; tar xvBf -"
Notice how we group the remote commands to clearly separate what we are running on the remote host from what we are doing locally. You might also use tar in conjunction with dd to read files from, or write files to, a tape device on a remote system. In the following command, we copy the files from the current directory and write them to a tape device on a remote host.
tar cvfb - 20 * | ssh boson dd of=/dev/rmt0 obs=20
Back-to-back tar commands have been used for many yef will be replaced with the uid and gid from this user. Keep that in mind, if you make backups/restore, practically always do any backup/restore with UID 0 (root).
If directories that are contained in tar archive exist the permissions will be changed to that in tar archive and files will be overwritten. If this is important system directory like /etc the net result can be a large SNAFU.
if you are not sure how tar archive was created it is safer to expand it first in /tmp and see results before restoring it to the original tree (especially if this is a system directory).
The use -f option to specify the file on which tar operates is the source of a log of grievances. This is not standard arrangement and as such it take time to get used to it.
Exclusion of files is tricky and you need to understand that basic regular expression are essentially applied to the line in the listing of tar with such files. If you do not use absolute path option there is no leading slash in such a listing and you can't use it to create your tar archive.
If tar became corrupted you still can recover most of files because of zero compression feature, but if such file compressed with gzip this is more tricky.
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Jul 20, 2017 | www.linuxjournal.com
Anonymous, 11/08/2002
At an unnamed location it happened thus... The customer had been using a home built 'tar' -based backup system for a long time. They were informed enough to have even tested and verified that recovery would work also.
Everything had been working fine, and they even had to do a recovery which went fine. Well, one day something evil happened to a disk and they had to replace the unit and do a full recovery.
Things looked fine until someone noticed that a directory with critically important and sensitive data was missing. Turned out that some manager had decided to 'secure' the directory by doing 'chmod 000 dir' to protect the data from inquisitive eyes when the data was not being used.
Of course, tar complained about the situation and returned with non-null status, but since the backup procedure had seemed to work fine, no one thought it necessary to view the logs...
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Jul 20, 2017 | www.linuxjournal.com
Anonymous on Fri, 11/08/2002 - 03:00.
Anonymous on Sun, 11/10/2002 - 03:00.The Subject, not the content, really brings back memories.
Imagine this, your tasked with complete control over the network in a multi-million dollar company. You've had some experience in the real world of network maintaince, but mostly you've learned from breaking things at home.
Time comes to implement (yes this was a startup company), a backup routine. You carefully consider the best way to do it and decide copying data to a holding disk before the tape run would be perfect in the situation, faster restore if the holding disk is still alive.
So off you go configuring all your servers for ssh pass through, and create the rsync scripts. Then before the trial run you think it would be a good idea to create a local backup of all the websites.
You logon to the web server, create a temp directory and start testing your newly advance rsync skills. After a couple of goes, you think your ready for the real thing, but you decide to run the test one more time.
Everything seems fine so you delete the temp directory. You pause for a second and your month drops open wider than it has ever opened before, and a feeling of terror overcomes you. You want to hide in a hole and hope you didn't see what you saw.
I RECURSIVELY DELETED ALL THE LIVE CORPORATE WEBSITES ON FRIDAY AFTERNOON AT 4PM!
This is why it's ALWAYS A GOOD IDEA to use Midnight Commander or something similar to delete directories!!
...Root for (5) years and never trashed a filesystem yet (knockwoody)...
Anonymous on Fri, 11/08/2002 - 03:00.
rsync with ssh as the transport mechanism works very well with my nightly LAN backups. I've found this page to be very helpful: http://www.mikerubel.org/computers/rsync_snapshots/
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Nov 01, 2018 | opensource.com
In a well-known data center (whose name I do not want to remember), one cold October night we had a production outage in which thousands of web servers stopped responding due to downtime in the main database. The database administrator asked me, the rookie sysadmin, to recover the database's last full backup and restore it to bring the service back online.
But, at the end of the process, the database was still broken. I didn't worry, because there were other full backup files in stock. However, even after doing the process several times, the result didn't change.
With great fear, I asked the senior sysadmin what to do to fix this behavior.
"You remember when I showed you, a few days ago, how the full backup script was running? Something about how important it was to validate the backup?" responded the sysadmin.
"Of course! You told me that I had to stay a couple of extra hours to perform that task," I answered. "Exactly! But you preferred to leave early without finishing that task," he said. "Oh my! I thought it was optional!" I exclaimed.
"It was, it was "
Moral of the story: Even with the best solution that promises to make the most thorough backups, the ghost of the failed restoration can appear, darkening our job skills, if we don't make a habit of validating the backup every time.
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Nov 08, 2002 | www.linuxjournal.com
Anonymous on Fri, 11/08/2002
Why don't you just buy an extra hard disk and have a copy of your important data there. With today's prices it doesn't cost anything.
Anonymous on Fri, 11/08/2002 - 03:00. A lot of people seams to have this idea, and in many situations it should work fine.
However, there is the human factor. Sometimes simple things go wrong (as simple as copying a file), and it takes a while before anybody notices that the contents of this file is not what is expected. This means you have to have many "generations" of backup of the file in order to be able to restore it, and in order to not put all the "eggs in the same basket" each of the file backups should be on a physical device.
Also, backing up to another disk in the same computer will probably not save you when lighting strikes, as the backup disk is just as likely to be fried as the main disk.
In real life, the backup strategy and hardware/software choices to support it is (as most other things) a balancing act. The important thing is that you have a strategy, and that you test it regularly to make sure it works as intended (as the main point is in the article). Also, realizing that achieving 100% backup security is impossible might save a lot of time in setting up the strategy.
(I.e. you have to say that this strategy has certain specified limits, like not being able to restore a file to its intermediate state sometime during a workday, only to the state it had when it was last backed up, which should be a maximum of xxx hours ago and so on...)
Hallvard P
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Feb 05, 2012 | www.mysysad.com
Frankly speaking, I did not want to waste time and bandwidth downloading images. Here is the syntax to exclude a directory.# tar cvfp mytarball.tar /mypath/Example.com_DIR --exclude=/mypath/Example.com_DIR/images
Tar everything in the current directory but exclude two files
# tar cvpf mytar.tar * --exclude=index.html --exclude=myimage.png
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Apr 28, 2018 | serverfault.com
up vote 2 down vote favorite 3
Im new to linux backup.
Im thinking of full system backup of my linux server using tar. I came up with the following code:tar -zcvpf /archive/fullbackup.tar.gz \ --exclude=/archive \ --exclude=/mnt \ --exclude=/proc \ --exclude=/lost+found \ --exclude=/dev \ --exclude=/sys \ --exclude=/tmp \ /and if in need of any hardware problem, restore it with
cd / tar -zxpvf fullbackup.tar.gzBut does my above code back up MBR and filesystem? Will the above code be enough to bring the same server back? linux backup tar share | improve this question edited Feb 14 '13 at 10:17
But does my above code back up MBR and filesystem?
Hennes 4,470 1 13 27
No. It backs up the contents of the filesystem.
Not the MBR which is not a file but is contained in a sector outside the file systems. And not the filesystem with it potentially tweaked settings and or errors, just the contents of the file system (granted, that is a minor difference).
and if in need of any hardware problem, restore it with
cd / tar -zxpvf fullbackup.tar.gzWill the above code be enough to bring the same server back?
Probably, as long as you use the same setup. The tarball will just contain the files, not the partition scheme used for the disks. So you will have to partition the disk in the same way. (Or copy the old partition scheme, e.g. with
dd if=/dev/sda of=myMBRbackup bs=512 count=1).Note that there are better ways to create backups, some of which already have been answered in other posts. Personally I would just backup the configuration and the data. Everything else is merely a matter of reinstalling. Possibly even with the latest version.
Also not that tar will backup all files. The first time that is a good thing.
But if you run that weekly or daily you will get a lot of large backups. In that case look at rsync (which does incremental changes) or one of the many other options. share | improve this answer edited Feb 14 '13 at 8:14 answered Feb 14 '13 at 7:29
- Could you paste the URL of other post for better ways to create backups? I have been looking for it but couldn't get the just way of doing it. – misamisa Feb 14 '13 at 22:37
- It depends on how you want to make backups. If you have several servers, try using Amanda ( amanda.org ), if you just have two servers use rsync (comes with the OS). If you have a build in tape drive use your tar command. If you want a once off backup with a nice graphical front consider Acronis True Image. Etc etc. – Hennes Feb 14 '13 at 22:41
- It's single Linux server (CentOS - shell access only) which I want to take a full system backup once. Once the backup is taken locally, I will transfer that backup to other PC to keep it safe. – misamisa Feb 14 '13 at 23:02
- In that case why create the backup on a server and then transfer it. You can do this instead: One the host to store your backup run
nc -l 1234 > MyBackupOfComputerA.tgz. And on the computer to archive run the tar command with as output filename-and append| nc ComputerB 1234. That-will write to std out instead of to a file. The|pipes the std out text to netcat which forwards it to another computer. The nc on the other computer listens for the information and writes it to a file. No intermediate copy is needed. – Hennes Feb 14 '13 at 23:05- As you told me above that the tar command won't backup the MBR and filesystem. I am looking for a way to have them in a backup in case of harddisk failure. – misamisa Feb 14 '13 at 23:08
Using tar to backup/restore a system is pretty rudimentary, and by that I mean that there are probably more elegant ways out there to backup your system... If you really want to stick to tar, here's a very good guide I found (it includes instructions on backing up the MBR; grub specifically).=: https://help.ubuntu.com/community/BackupYourSystem/TAR While it's on the Ubuntu wiki website, there's no reason why it wouldn't work on any UNIX/Linux machine.
You may also wish to check out this: https://help.ubuntu.com/community/BackupYourSystem
If you'd like something with a nice web GUI that's relatively straightforward to set up and use: http://backuppc.sourceforge.net/
Floyd Feb 14 '13 at 6:40
- 1 Let me second the pointer to backuppc. If you have several machines to backup, backuppc is a dream come true. Best thing of it is it's deduplication and compression. –
Using remastersys :
You can create live iso of your existing system. so install all the required packages on your ubuntu and then take a iso using remastersys. Then using startup disk, you can create bootable usb from this iso.
edit your /etc/apt/sources.list file. Add the following line in the end of the file.
deb http://www.remastersys.com/ubuntu precise main
Then run the following command:
sudo apt-get update
sudo apt-get install remastersys
sudo apt-get install remastersys-gui
sudo apt-get install remastersys-gtk
To run the remastersys in gui mode, type the following command:
sudo remastersys-gui share | improve this answer
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Apr 28, 2018 | www.lylebackenroth.com
Source: help.ubuntu.com
Preparing for backup
Just a quick note. You are about to back up your entire system. Don't forget to empty your Wastebasket, remove any unwanted files in your /home directory, and cleanup your desktop.
Depending on why you're backing up, you might want to: Delete all your emails; Clear your browser search history; Wipe your saved browser personal details
- Unmount any external media devices, and remove any CDs/DVDs not needed for the backup process.
- This will lessen the amount of exclusions you need to type later in the process.
.... ... ...
Files that are bigger than 2GB are not supported by some implementations of ISO9660 and may not be restorable. So don't simply burn a DVD with a huge .iso file on it. Split it up using the command split or use a different way to get it onto the DVD. See man split for further information on split.
A possible workaround is the following:
sudo tar –create –bzip2 –exclude /tmp –one-file-system –sparse / | growisofs -use-the-force-luke -Z /dev/hda=/proc/self/fd/0
Note that this only backs up one file system. You might want to use –exclude instead of –one-file-system to filter out the stuff you don't want backed up. This assumes your DVD drive is /dev/hda. This will not create a mountable DVD. To restore it you will reference the device file:
sudo tar –extract –bzip2 –file /dev/hda
At the end of the process you might get a message along the lines of 'tar: Error exit delayed from previous errors' or something, but in most cases you can just ignore that.
Another workaround would be to Bzip2 to compress your backup. Bzip2 provides a higher compression ratio at the expense of speed. If compression is important to you, just substitute the z in the command with j, and change the file name to backup.tar.bz2 . That would make the command look like this:
tar -cvpjf /backup.tar.bz2 –exclude=/proc –exclude=/lost+found –exclude=/backup.tar.bz2 –exclude=/mnt –exclude=/sys /
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tar listing.Apr 28, 2018 | stackoverflow.com
Udo G ,May 9, 2012 at 7:13
I'm usingtarto make daily backups of a server and want to avoid backup of /proc and /sys system directories, but without excluding any directories named "proc" or "sys" somewhere else in the file tree.For, example having the following directory tree (" bla " being normal files):
# find . ./sys ./sys/bla ./foo ./foo/sys ./foo/sys/blaI would like to exclude
./sysbut not./foo/sys.I can't seem to find an
--excludepattern that does that...# tar cvf /dev/null * --exclude=sys foo/or...
# tar cvf /dev/null * --exclude=/sys foo/ foo/sys/ foo/sys/bla sys/ sys/blaAny ideas? (Linux Debian 6)
drinchev ,May 9, 2012 at 7:19
Are you sure there is no exclude? If you are using MAC OS it is a different story! Look here – drinchev May 9 '12 at 7:19Udo G ,May 9, 2012 at 7:21
Not sure I understand your question. There is a--excludeoption, but I don't know how to match it for single, absolute file names (not any file by that name) - see my examples above. – Udo G May 9 '12 at 7:21paulsm4 ,May 9, 2012 at 7:22
Look here: stackoverflow.com/questions/984204/ – paulsm4 May 9 '12 at 7:22CharlesB ,May 9, 2012 at 7:29
You can specify absolute paths to the exclude pattern, this way othersysorprocdirectories will be archived:tar --exclude=/sys --exclude=/proc /Udo G ,May 9, 2012 at 7:34
True, but the important detail about this is that the excluded file name must match exactly the notation reported by thetarlisting. For my example that would be./sys- as I just found out now. – Udo G May 9 '12 at 7:34pjv ,Apr 9, 2013 at 18:14
In this case you might want to use:--anchored --exclude=sys/\*because in case your tar does not show the leading "/" you have a problem with the filter.
Savvas Radevic ,May 9, 2013 at 10:44
This did the trick for me, thank you! I wanted to exclude a specific directory, not all directories/subdirectories matching the pattern. bsdtar does not have "--anchored" option though, and with bsdtar we can use full paths to exclude specific folders. – Savvas Radevic May 9 '13 at 10:44Savvas Radevic ,May 9, 2013 at 10:58
ah found it! in bsdtar the anchor is "^":bsdtar cvjf test.tar.bz2 --exclude myfile.avi --exclude "^myexcludedfolder" *– Savvas Radevic May 9 '13 at 10:58Stephen Donecker ,Nov 8, 2012 at 19:12
Using tar you can exclude directories by placing a tag file in any directory that should be skipped.Create tag files,
touch /sys/.exclude_from_backup touch /proc/.exclude_from_backupThen,
tar -czf backup.tar.gz --exclude-tag-all=.exclude_from_backup *pjv ,Apr 9, 2013 at 17:58
Good idea in theory but often /sys and /proc cannot be written to. – pjv Apr 9 '13 at 17:58
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Apr 27, 2018 | stackoverflow.com
deepwell ,Jun 11, 2009 at 22:57
Is there a simple shell command/script that supports excluding certain files/folders from being archived?I have a directory that need to be archived with a sub directory that has a number of very large files I do not need to backup.
Not quite solutions:
The
tar --exclude=PATTERNcommand matches the given pattern and excludes those files, but I need specific files & folders to be ignored (full file path), otherwise valid files might be excluded.I could also use the find command to create a list of files and exclude the ones I don't want to archive and pass the list to tar, but that only works with for a small amount of files. I have tens of thousands.
I'm beginning to think the only solution is to create a file with a list of files/folders to be excluded, then use rsync with
--exclude-from=fileto copy all the files to a tmp directory, and then use tar to archive that directory.Can anybody think of a better/more efficient solution?
EDIT: cma 's solution works well. The big gotcha is that the
--exclude='./folder'MUST be at the beginning of the tar command. Full command (cd first, so backup is relative to that directory):cd /folder_to_backup tar --exclude='./folder' --exclude='./upload/folder2' -zcvf /backup/filename.tgz .Rekhyt ,May 1, 2012 at 12:55
Another thing caught me out on that, might be worth a note:Trailing slashes at the end of excluded folders will cause tar to not exclude those folders at all. – Rekhyt May 1 '12 at 12:55
Brice ,Jun 24, 2014 at 16:06
I had to remove the single quotation marks in order to exclude sucessfully the directories. (tar -zcvf gatling-charts-highcharts-1.4.6.tar.gz /opt/gatling-charts-highcharts-1.4.6 --exclude=results --exclude=target) – Brice Jun 24 '14 at 16:06Charles Ma ,Jun 11, 2009 at 23:11
You can have multiple exclude options for tar so$ tar --exclude='./folder' --exclude='./upload/folder2' -zcvf /backup/filename.tgz .etc will work. Make sure to put
--excludebefore the source and destination items.shasi kanth ,Feb 27, 2015 at 10:49
As an example, if you are trying to backup your wordpress project folder, excluding the uploads folder, you can use this command:tar -cvf wordpress_backup.tar wordpress --exclude=wp-content/uploads –
Alfred Bez ,Jul 16, 2015 at 7:28
I came up with the following command:tar -zcv --exclude='file1' --exclude='pattern*' --exclude='file2' -f /backup/filename.tgz .note that the-fflag needs to precede the tar file see:flickerfly ,Aug 21, 2015 at 16:22
A "/" on the end of the exclude directory will cause it to fail. I guess tar thinks an ending / is part of the directory name to exclude. BAD: --exclude=mydir/ GOOD: --exclude=mydir – flickerfly Aug 21 '15 at 16:22NightKnight on Cloudinsidr.com ,Nov 24, 2016 at 9:55
> Make sure to put --exclude before the source and destination items. OR use an absolute path for the exclude: tar -cvpzf backups/target.tar.gz --exclude='/home/username/backups' /home/username – NightKnight on Cloudinsidr.com Nov 24 '16 at 9:55Johan Soderberg ,Jun 11, 2009 at 23:10
To clarify, you can use full path for --exclude. – Johan Soderberg Jun 11 '09 at 23:10Stephen Donecker ,Nov 8, 2012 at 0:22
Possible options to exclude files/directories from backup using tar:Exclude files using multiple patterns
tar -czf backup.tar.gz --exclude=PATTERN1 --exclude=PATTERN2 ... /path/to/backupExclude files using an exclude file filled with a list of patterns
tar -czf backup.tar.gz -X /path/to/exclude.txt /path/to/backupExclude files using tags by placing a tag file in any directory that should be skipped
tar -czf backup.tar.gz --exclude-tag-all=exclude.tag /path/to/backupAnish Ramaswamy ,May 16, 2015 at 0:11
This answer definitely helped me! The gotcha for me was that my command looked something liketar -czvf mysite.tar.gz mysite --exclude='./mysite/file3' --exclude='./mysite/folder3', and this didn't exclude anything. – Anish Ramaswamy May 16 '15 at 0:11Hubert ,Feb 22, 2017 at 7:38
Nice and clear thank you. For me the issue was that other answers include absolute or relative paths. But all you have to do is add the name of the folder you want to exclude. – Hubert Feb 22 '17 at 7:38GeertVc ,Dec 31, 2013 at 13:35
Just want to add to the above, that it is important that the directory to be excluded should NOT contain a final backslash. So, --exclude='/path/to/exclude/dir' is CORRECT , --exclude='/path/to/exclude/dir/' is WRONG . – GeertVc Dec 31 '13 at 13:35Eric Manley ,May 14, 2015 at 14:10
You can use standard "ant notation" to exclude directories relative.
This works for me and excludes any .git or node_module directories.tar -cvf myFile.tar --exclude=**/.git/* --exclude=**/node_modules/* -T /data/txt/myInputFile.txt 2> /data/txt/myTarLogFile.txtmyInputFile.txt Contains:
/dev2/java
/dev2/javascriptnot2qubit ,Apr 4 at 3:24
I believe this require that the Bash shell option variableglobstarhas to be enabled. Check withshopt -s globstar. I think it off by default on most unix based OS's. From Bash manual: " globstar: If set, the pattern**used in a filename expansion context will match all files and zero or more directories and subdirectories. If the pattern is followed by a '/', only directories and subdirectories match. " – not2qubit Apr 4 at 3:24Benoit Duffez ,Jun 19, 2016 at 21:14
Don't forgetCOPYFILE_DISABLE=1when using tar, otherwise you may get ._ files in your tarball – Benoit Duffez Jun 19 '16 at 21:14Scott Stensland ,Feb 12, 2015 at 20:55
This exclude pattern handles filename suffix like png or mp3 as well as directory names like .git and node_modulestar --exclude={*.png,*.mp3,*.wav,.git,node_modules} -Jcf ${target_tarball} ${source_dirname}Alex B ,Jun 11, 2009 at 23:03
Use the find command in conjunction with the tar append (-r) option. This way you can add files to an existing tar in a single step, instead of a two pass solution (create list of files, create tar).find /dir/dir -prune ... -o etc etc.... -exec tar rvf ~/tarfile.tar {} \;carlo ,Mar 4, 2012 at 15:18
To avoid possible'xargs: Argument list too long'errors due to the use offind ... | xargs ...when processing tens of thousands of files, you can pipe the output offinddirectly totarusingfind ... -print0 | tar --null ....# archive a given directory, but exclude various files & directories # specified by their full file paths find "$(pwd -P)" -type d \( -path '/path/to/dir1' -or -path '/path/to/dir2' \) -prune \ -or -not \( -path '/path/to/file1' -or -path '/path/to/file2' \) -print0 | gnutar --null --no-recursion -czf archive.tar.gz --files-from - #bsdtar --null -n -czf archive.tar.gz -T -Znik ,Mar 4, 2014 at 12:20
you can quote 'exclude' string, like this: 'somedir/filesdir/*' then shell isn't going to expand asterisks and other white chars.Tuxdude ,Nov 15, 2014 at 5:12
xargs -n 1is another option to avoidxargs: Argument list too longerror ;) – Tuxdude Nov 15 '14 at 5:12Aaron Votre ,Jul 15, 2016 at 15:56
I agree the --exclude flag is the right approach.$ tar --exclude='./folder_or_file' --exclude='file_pattern' --exclude='fileA'A word of warning for a side effect that I did not find immediately obvious: The exclusion of 'fileA' in this example will search for 'fileA' RECURSIVELY!
Example:A directory with a single subdirectory containing a file of the same name (data.txt)
data.txt config.txt --+dirA | data.txt | config.docx
- If using
--exclude='data.txt'the archive will not contain EITHER data.txt file. This can cause unexpected results if archiving third party libraries, such as a node_modules directory.- To avoid this issue make sure to give the entire path, like
--exclude='./dirA/data.txt'Mike ,May 9, 2014 at 21:26
After reading this thread, I did a little testing on RHEL 5 and here are my results for tarring up the abc directory:This will exclude the directories error and logs and all files under the directories:
tar cvpzf abc.tgz abc/ --exclude='abc/error' --exclude='abc/logs'Adding a wildcard after the excluded directory will exclude the files but preserve the directories:
tar cvpzf abc.tgz --exclude='abc/error/*' --exclude='abc/logs/*' abc/camh ,Jun 12, 2009 at 5:53
You can use cpio(1) to create tar files. cpio takes the files to archive on stdin, so if you've already figured out the find command you want to use to select the files the archive, pipe it into cpio to create the tar file:find ... | cpio -o -H ustar | gzip -c > archive.tar.gzfrommelmak ,Sep 10, 2012 at 14:08
You can also use one of the "--exclude-tag" options depending on your needs:
- --exclude-tag=FILE
- --exclude-tag-all=FILE
- --exclude-tag-under=FILE
The folder hosting the specified FILE will be excluded.
Joe ,Jun 11, 2009 at 23:04
Your best bet is to use find with tar, via xargs (to handle the large number of arguments). For example:find / -print0 | xargs -0 tar cjf tarfile.tar.bz2jørgensen ,Mar 4, 2012 at 15:23
That can cause tar to be invoked multiple times - and will also pack files repeatedly. Correct is:find / -print0 | tar -T- --null --no-recursive -cjf tarfile.tar.bz2– jørgensen Mar 4 '12 at 15:23Stphane ,Dec 19, 2015 at 11:10
I read somewhere that when usingxargs, one should use tarroption instead ofcbecause whenfindactually finds loads of results, the xargs will split those results (based on the local command line arguments limit) into chuncks and invoke tar on each part. This will result in a archive containing the last chunck returned byxargsand not all results found by thefindcommand. – Stphane Dec 19 '15 at 11:10Andrew ,Apr 14, 2014 at 16:21
gnu tar v 1.26 the --exclude needs to come after archive file and backup directory arguments, should have no leading or trailing slashes, and prefers no quotes (single or double). So relative to the PARENT directory to be backed up, it's:
tar cvfz /path_to/mytar.tgz ./dir_to_backup --exclude=some_path/to_excludeAshwini Gupta ,Jan 12 at 10:30
tar -cvzf destination_folder source_folder -X /home/folder/excludes.txt-X indicates a file which contains a list of filenames which must be excluded from the backup. For Instance, you can specify *~ in this file to not include any filenames ending with ~ in the backup.
Georgios ,Sep 4, 2013 at 22:35
Possible redundant answer but since I found it useful, here it is:While a FreeBSD root (i.e. using csh) I wanted to copy my whole root filesystem to /mnt but without /usr and (obviously) /mnt. This is what worked (I am at /):
tar --exclude ./usr --exclude ./mnt --create --file - . (cd /mnt && tar xvd -)My whole point is that it was necessary (by putting the ./ ) to specify to tar that the excluded directories where part of the greater directory being copied.
My €0.02
user2792605 ,Sep 30, 2013 at 20:07
I had no luck getting tar to exclude a 5 Gigabyte subdirectory a few levels deep. In the end, I just used the unix Zip command. It worked a lot easier for me.So for this particular example from the original post
(tar --exclude='./folder' --exclude='./upload/folder2' -zcvf /backup/filename.tgz . )The equivalent would be:
zip -r /backup/filename.zip . -x upload/folder/**\* upload/folder2/**\*
(NOTE: Here is the post I originally used that helped me https://superuser.com/questions/312301/unix-zip-directory-but-excluded-specific-subdirectories-and-everything-within-t )
t0r0X ,Sep 29, 2014 at 20:25
Beware:zipdoes not pack empty directories, buttardoes! – t0r0X Sep 29 '14 at 20:25RohitPorwal ,Jul 21, 2016 at 9:56
Check it outtar cvpzf zip_folder.tgz . --exclude=./public --exclude=./tmp --exclude=./log --exclude=fileNameJames ,Oct 28, 2016 at 14:01
The following bash script should do the trick. It uses the answer given here by Marcus Sundman.#!/bin/bash echo -n "Please enter the name of the tar file you wish to create with out extension " read nam echo -n "Please enter the path to the directories to tar " read pathin echo tar -czvf $nam.tar.gz excludes=`find $pathin -iname "*.CC" -exec echo "--exclude \'{}\'" \;|xargs` echo $pathin echo tar -czvf $nam.tar.gz $excludes $pathinThis will print out the command you need and you can just copy and paste it back in. There is probably a more elegant way to provide it directly to the command line.
Just change *.CC for any other common extension, file name or regex you want to exclude and this should still work.
EDIT
Just to add a little explanation; find generates a list of files matching the chosen regex (in this case *.CC). This list is passed via xargs to the echo command. This prints --exclude 'one entry from the list'. The slashes () are escape characters for the ' marks.
tripleee ,Sep 14, 2017 at 4:27
Requiring interactive input is a poor design choice for most shell scripts. Make it read command-line parameters instead and you get the benefit of the shell's tab completion, history completion, history editing, etc. – tripleee Sep 14 '17 at 4:27tripleee ,Sep 14, 2017 at 4:38
Additionally, your script does not work for paths which contain whitespace or shell metacharacters. You should basically always put variables in double quotes unless you specifically require the shell to perform whitespace tokenization and wildcard expansion. For details, please see stackoverflow.com/questions/10067266/ – tripleee Sep 14 '17 at 4:38> ,Apr 18 at 0:31
For those who have issues with it, some versions of tar would only work properly without the './' in the exclude value.Tar --versiontar (GNU tar) 1.27.1
Command syntax that work:
tar -czvf ../allfiles-butsome.tar.gz * --exclude=acme/fooThese will not work:
$ tar -czvf ../allfiles-butsome.tar.gz * --exclude=./acme/foo $ tar -czvf ../allfiles-butsome.tar.gz * --exclude='./acme/foo' $ tar --exclude=./acme/foo -czvf ../allfiles-butsome.tar.gz * $ tar --exclude='./acme/foo' -czvf ../allfiles-butsome.tar.gz * $ tar -czvf ../allfiles-butsome.tar.gz * --exclude=/full/path/acme/foo $ tar -czvf ../allfiles-butsome.tar.gz * --exclude='/full/path/acme/foo' $ tar --exclude=/full/path/acme/foo -czvf ../allfiles-butsome.tar.gz * $ tar --exclude='/full/path/acme/foo' -czvf ../allfiles-butsome.tar.gz *
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Nov 08, 2002 | www.linuxjournal.com
Anonymous on Fri, 11/08/2002 - 03:00.
Its here .. Unbeliveable..
[I had intended to leave the discussion of "rm -r *" behind after the compendium I sent earlier, but I couldn't resist this one.
I also received a response from rutgers!seismo!hadron!jsdy (Joseph S. D. Yao) that described building a list of "dangerous" commands into a shell and dropping into a query when a glob turns up. They built it in so it couldn't be removed, like an alias. Anyway, on to the story! RWH.] I didn't see the message that opened up the discussion on rm, but thought you might like to read this sorry tale about the perils of rm....
(It was posted to net.unix some time ago, but I think our postnews didn't send it as far as it should have!)
----------------------------------------------------------------
Have you ever left your terminal logged in, only to find when you came back to it that a (supposed) friend had typed "rm -rf ~/*" and was hovering over the keyboard with threats along the lines of "lend me a fiver 'til Thursday, or I hit return"? Undoubtedly the person in question would not have had the nerve to inflict such a trauma upon you, and was doing it in jest. So you've probably never experienced the worst of such disasters....
It was a quiet Wednesday afternoon. Wednesday, 1st October, 15:15 BST, to be precise, when Peter, an office-mate of mine, leaned away from his terminal and said to me, "Mario, I'm having a little trouble sending mail." Knowing that msg was capable of confusing even the most capable of people, I sauntered over to his terminal to see what was wrong. A strange error message of the form (I forget the exact details) "cannot access /foo/bar for userid 147" had been issued by msg.
My first thought was "Who's userid 147?; the sender of the message, the destination, or what?" So I leant over to another terminal, already logged in, and typed
grep 147 /etc/passwdonly to receive the response
/etc/passwd: No such file or directory.Instantly, I guessed that something was amiss. This was confirmed when in response to
ls /etcI got
ls: not found.I suggested to Peter that it would be a good idea not to try anything for a while, and went off to find our system manager. When I arrived at his office, his door was ajar, and within ten seconds I realised what the problem was. James, our manager, was sat down, head in hands, hands between knees, as one whose world has just come to an end. Our newly-appointed system programmer, Neil, was beside him, gazing listlessly at the screen of his terminal. And at the top of the screen I spied the following lines:
# cd # rm -rf *Oh, *****, I thought. That would just about explain it.
I can't remember what happened in the succeeding minutes; my memory is just a blur. I do remember trying ls (again), ps, who and maybe a few other commands beside, all to no avail. The next thing I remember was being at my terminal again (a multi-window graphics terminal), and typing
cd / echo *I owe a debt of thanks to David Korn for making echo a built-in of his shell; needless to say, /bin, together with /bin/echo, had been deleted. What transpired in the next few minutes was that /dev, /etc and /lib had also gone in their entirety; fortunately Neil had interrupted rm while it was somewhere down below /news, and /tmp, /usr and /users were all untouched.
Meanwhile James had made for our tape cupboard and had retrieved what claimed to be a dump tape of the root filesystem, taken four weeks earlier. The pressing question was, "How do we recover the contents of the tape?". Not only had we lost /etc/restore, but all of the device entries for the tape deck had vanished. And where does mknod live?
You guessed it, /etc.
How about recovery across Ethernet of any of this from another VAX? Well, /bin/tar had gone, and thoughtfully the Berkeley people had put rcp in /bin in the 4.3 distribution. What's more, none of the Ether stuff wanted to know without /etc/hosts at least. We found a version of cpio in /usr/local, but that was unlikely to do us any good without a tape deck.
Alternatively, we could get the boot tape out and rebuild the root filesystem, but neither James nor Neil had done that before, and we weren't sure that the first thing to happen would be that the whole disk would be re-formatted, losing all our user files. (We take dumps of the user files every Thursday; by Murphy's Law this had to happen on a Wednesday).
Another solution might be to borrow a disk from another VAX, boot off that, and tidy up later, but that would have entailed calling the DEC engineer out, at the very least. We had a number of users in the final throes of writing up PhD theses and the loss of a maybe a weeks' work (not to mention the machine down time) was unthinkable.
So, what to do? The next idea was to write a program to make a device descriptor for the tape deck, but we all know where cc, as and ld live. Or maybe make skeletal entries for /etc/passwd, /etc/hosts and so on, so that /usr/bin/ftp would work. By sheer luck, I had a gnuemacs still running in one of my windows, which we could use to create passwd, etc., but the first step was to create a directory to put them in.
Of course /bin/mkdir had gone, and so had /bin/mv, so we couldn't rename /tmp to /etc. However, this looked like a reasonable line of attack.
By now we had been joined by Alasdair, our resident UNIX guru, and as luck would have it, someone who knows VAX assembler. So our plan became this: write a program in assembler which would either rename /tmp to /etc, or make /etc, assemble it on another VAX, uuencode it, type in the uuencoded file using my gnu, uudecode it (some bright spark had thought to put uudecode in /usr/bin), run it, and hey presto, it would all be plain sailing from there. By yet another miracle of good fortune, the terminal from which the damage had been done was still su'd to root (su is in /bin, remember?), so at least we stood a chance of all this working.
Off we set on our merry way, and within only an hour we had managed to concoct the dozen or so lines of assembler to create /etc. The stripped binary was only 76 bytes long, so we converted it to hex (slightly more readable than the output of uuencode), and typed it in using my editor. If any of you ever have the same problem, here's the hex for future reference:
070100002c000000000000000000000000000000000000000000000000000000 0000dd8fff010000dd8f27000000fb02ef07000000fb01ef070000000000bc8f 8800040000bc012f65746300I had a handy program around (doesn't everybody?) for converting ASCII hex to binary, and the output of /usr/bin/sum tallied with our original binary. But hang on---how do you set execute permission without /bin/chmod? A few seconds thought (which as usual, lasted a couple of minutes) suggested that we write the binary on top of an already existing binary, owned by me...problem solved.
So along we trotted to the terminal with the root login, carefully remembered to set the umask to 0 (so that I could create files in it using my gnu), and ran the binary. So now we had a /etc, writable by all.
From there it was but a few easy steps to creating passwd, hosts, services, protocols, (etc), and then ftp was willing to play ball. Then we recovered the contents of /bin across the ether (it's amazing how much you come to miss ls after just a few, short hours), and selected files from /etc. The key file was /etc/rrestore, with which we recovered /dev from the dump tape, and the rest is history.
Now, you're asking yourself (as I am), what's the moral of this story? Well, for one thing, you must always remember the immortal words, DON'T PANIC. Our initial reaction was to reboot the machine and try everything as single user, but it's unlikely it would have come up without /etc/init and /bin/sh. Rational thought saved us from this one.
The next thing to remember is that UNIX tools really can be put to unusual purposes. Even without my gnuemacs, we could have survived by using, say, /usr/bin/grep as a substitute for /bin/cat. And the final thing is, it's amazing how much of the system you can delete without it falling apart completely. Apart from the fact that nobody could login (/bin/login?), and most of the useful commands had gone, everything else seemed normal. Of course, some things can't stand life without say /etc/termcap, or /dev/kmem, or /etc/utmp, but by and large it all hangs together.
I shall leave you with this question: if you were placed in the same situation, and had the presence of mind that always comes with hindsight, could you have got out of it in a simpler or easier way?
Answers on a postage stamp to:
Mario Wolczko
------------------------------------------------------------------------
Dept. of Computer Science ARPA: miw%uk.ac.man.cs.ux@cs.ucl.ac.uk
The University USENET: mcvax!ukc!man.cs.ux!miw
Manchester M13 9PL JANET: miw@uk.ac.man.cs.ux
U.K. 061-273 7121 x 5699
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Jul 20, 2017 | www.makeuseof.com
Back in college, I used to work just about every day as a computer cluster consultant. I remember a month after getting promoted to a supervisor, I was in the process of training a new consultant in the library computer cluster. Suddenly, someone tapped me on the shoulder, and when I turned around I was confronted with a frantic graduate student – a 30-something year old man who I believe was Eastern European based on his accent – who was nearly in tears."Please need help – my document is all gone and disk stuck!" he said as he frantically pointed to his PC.
Now, right off the bat I could have told you three facts about the guy. One glance at the blue screen of the archaic DOS-based version of Wordperfect told me that – like most of the other graduate students at the time – he had not yet decided to upgrade to the newer, point-and-click style word processing software. For some reason, graduate students had become so accustomed to all of the keyboard hot-keys associated with typing in a DOS-like environment that they all refused to evolve into point-and-click users.
The second fact, gathered from a quick glance at his blank document screen and the sweat on his brow told me that he had not saved his document as he worked. The last fact, based on his thick accent, was that communicating the gravity of his situation wouldn't be easy. In fact, it was made even worse by his answer to my question when I asked him when he last saved.
"I wrote 30 pages."
Calculated out at about 600 words a page, that's 18000 words. Ouch.
Then he pointed at the disk drive. The floppy disk was stuck, and from the marks on the drive he had clearly tried to get it out with something like a paper clip. By the time I had carefully fished the torn and destroyed disk out of the drive, it was clear he'd never recover anything off of it. I asked him what was on it.
"My thesis."
I gulped. I asked him if he was serious. He was. I asked him if he'd made any backups. He hadn't.
Making Backups of BackupsIf there is anything I learned during those early years of working with computers (and the people that use them), it was how critical it is to not only save important stuff, but also to save it in different places. I would back up floppy drives to those cool new zip drives as well as the local PC hard drive. Never, ever had a single copy of anything.
Unfortunately, even today, people have not learned that lesson. Whether it's at work, at home, or talking with friends, I keep hearing stories of people losing hundreds to thousands of files, sometimes they lose data worth actual dollars in time and resources that were used to develop the information.
To drive that lesson home, I wanted to share a collection of stories that I found around the Internet about some recent cases were people suffered that horrible fate – from thousands of files to entire drives worth of data completely lost. These are people where the only remaining option is to start running recovery software and praying, or in other cases paying thousands of dollars to a data recovery firm and hoping there's something to find.
Not Backing Up ProjectsThe first example comes from Yahoo Answers , where a user that only provided a "?" for a user name (out of embarrassment probably), posted:
"I lost all my files from my hard drive? help please? I did a project that took me 3 days and now i lost it, its powerpoint presentation, where can i look for it? its not there where i save it, thank you"
The folks answering immediately dove into suggesting that the person run recovery software, and one person suggested that the person run a search on the computer for *.ppt.
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Doing Backups Wrong
Then, there's a scenario of actually trying to do a backup and doing it wrong, losing all of the files on the original drive. That was the case for the person who posted on Tech Support Forum , that after purchasing a brand new Toshiba Laptop and attempting to transfer old files from an external hard drive, inadvertently wiped the files on the hard drive.
Please someone help me I last week brought a Toshiba Satellite laptop running windows 7, to replace my blue screening Dell vista laptop. On plugged in my sumo external hard drive to copy over some much treasured photos and some of my (work – music/writing.) it said installing driver. it said completed I clicked on the hard drive and found a copy of my documents from the new laptop and nothing else.
While the description of the problem is a little broken, from the sound of it, the person thought they were backing up from one direction, while they were actually backing up in the other direction. At least in this case not all of the original files were deleted, but a majority were.
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May 01, 2018 | Techdirt
Here's a random story, found via Kottke , highlighting how Pixar came very close to losing a very large portion of Toy Story 2 , because someone did an rm * (non geek: "remove all" command). And that's when they realized that their backups hadn't been working for a month. Then, the technical director of the film noted that, because she wanted to see her family and kids, she had been making copies of the entire film and transferring it to her home computer. After a careful trip from the Pixar offices to her home and back, they discovered that, indeed, most of the film was saved:
Now, mostly, this is just an amusing little anecdote, but two things struck me: How in the world do they not have more "official" backups of something as major as Toy Story 2 . In the clip they admit that it was potentially 20 to 30 man-years of work that may have been lost. It makes no sense to me that this would include a single backup system. I wonder if the copy, made by technical director Galyn Susman, was outside of corporate policy. You would have to imagine that at a place like Pixar, there were significant concerns about things "getting out," and so the policy likely wouldn't have looked all that kindly on copies being used on home computers.
The Mythbusters folks wonder if this story was a little over-dramatized , and others have wondered how the technical director would have "multiple terabytes of source material" on her home computer back in 1999. That resulted in an explanation from someone who was there that what was deleted was actually the database containing the master copies of the characters, sets, animation, etc. rather than the movie itself. Of course, once again, that makes you wonder how it is that no one else had a simple backup. You'd think such a thing would be backed up in dozens of places around the globe for safe keeping...
Hans B PUFAL ( profile ), 18 May 2012 @ 5:53amReminds me of .... Some decades ago I was called to a customer site, a bank, to diagnose a computer problem. On my arrival early in the morning I noted a certain panic in the air. On querying my hosts I was told that there had been an "issue" the previous night and that they were trying, unsuccessfully, to recover data from backup tapes. The process was failing and panic ensued.Anonymous Coward , 18 May 2012 @ 6:00amThough this was not the problem I had been called on to investigate, I asked some probing questions, made a short phone call, and provided the answer, much to the customer's relief.
What I found was that for months if not years the customer had been performing backups of indexed sequential files, that is data files with associated index files, without once verifying that the backed-up data could be recovered. On the first occasion of a problem requiring such a recovery they discovered that they just did not work.
The answer? Simply recreate the index files from the data. For efficiency reasons (this was a LONG time ago) the index files referenced the data files by physical disk addresses. When the backup tapes were restored the data was of course no longer at the original place on the disk and the index files were useless. A simple procedure to recreate the index files solved the problem.
Clearly whoever had designed that system had never tested a recovery, nor read the documentation which clearly stated the issue and its simple solution.
So here is a case of making backups, but then finding them flawed when needed.
Re: Reminds me of .... That's why, in the IT world, you ALWAYS do a "dry run" when you want to deploy something, and you monitor the heck out of critical systems.Rich Kulawiec , 18 May 2012 @ 6:30amTwo notes on backupssaulgoode ( profile ), 18 May 2012 @ 6:38am1. Everyone who has worked in computing for any period of time has their own backup horror story. I'll spare you mine, but note that as a general observation, large organizations/corporations tend to opt for incredibly expensive, incredibly complex, incredibly overblown backup "solutions" sold to them by vendors rather than using the stock, well-tested, reliable tools that they already have. (e.g., "why should we use dump, which is open-source/reliable/portable/tested/proven/efficient/etc., when we could drop $40K on closed-source/proprietary/non-portable/slow/bulky software from a vendor?"
Okay, okay, one comment: in over 30 years of working in the field, the second-worst product I have ever had the misfortune to deal with is Legato (now EMC) NetWorker.
2. Hollywood has a massive backup and archiving problem. How do we know? Because they keep telling us about it. There are a series of self-promoting commercials that they run in theaters before movies, in which they talk about all of the old films that are slowly decaying in their canisters in vast warehouses, and how terrible this is, and how badly they need charitable contributions from the public to save these treasures of cinema before they erode into dust, etc.
Let's skip the irony of Hollywood begging for money while they're paying professional liar Chris Dodd millions and get to the technical point: the easiest and cheapest way to preserve all of these would be to back them up to the Internet. Yes, there's a one-time expense of cleaning up the analog versions and then digitizing them at high resolution, but once that's done, all the copies are free. There's no need for a data center or elaborate IT infrastructure: put 'em on BitTorrent and let the world do the work. Or give copies to the Internet Archive. Whatever -- the point is that once we get past the analog issues, the only reason that this is a problem is that they
made it a problem by refusing to surrender control.Re: Two notes on backups "Real Men don't make backups. They upload it via ftp and let the world mirror it." - Linus TorvaldsAnonymous Coward , 18 May 2012 @ 7:02amWhat I suspect is that she was copying the rendered footage. If the footage was rendered at a resolution and rate fitting to DVD spec, that'd put the raw footage at around 3GB to 4GB for a full 90min, which just might fit on the 10GB HDD that were available back then on a laptop computer (remember how small OSes were back then).aldestrawk ( profile ), 18 May 2012 @ 8:34amEven losing just the rendered raw footage (or even processed footage), would be a massive setback. It takes a long time across a lot of very powerful computers to render film quality footage. If it was processed footage then it's even more valuable as that takes a lot of man hours of post fx to make raw footage presentable to a consumer audience.
a retelling by Oren Jacob Oren Jacob, the Pixar director featured in the animation, has made a comment on the Quora post that explains things in much more detail. The narration and animation was telling a story, as in storytelling. Despite the 99% true caption at the end, a lot of details were left out which misrepresented what had happened. Still, it was a fun tale for anyone who had dealt with backup problems. Oren Jacob's retelling in the comment makes it much more realistic and believable.Mason Wheeler , 18 May 2012 @ 10:01am
The terabytes level of data came from whoever posted the video on Quora. The video itself never mentions the actual amount of data lost or the total amount the raw files represent. Oren says, vaguely, that it was much less than a terabyte. There were backups! The last one was from two days previous to the delete event. The backup was flawed in that it produced files that when tested, by rendering, exhibited errors.They ended up patching a two-month old backup together with the home computer version (two weeks old). This was labor intensive as some 30k files had to be individually checked.
The moral of the story.
- Firstly, always test a restore at some point when implementing a backup system.
- Secondly, don't panic! Panic can lead to further problems. They could well have introduced corruption in files by abruptly unplugging the computer.
- Thirdly, don't panic! Despite, somehow, deleting a large set of files these can be recovered apart from a backup system.
Deleting files, under Linux as well as just about any OS, only involves deleting the directory entries. There is software which can recover those files as long as further use of the computer system doesn't end up overwriting what is now free space.
Re: a retelling by Oren Jacobaldestrawk ( profile ), 18 May 2012 @ 10:38amPanic can lead to further problems. They could well have introduced corruption in files by abruptly unplugging the computer.What's worse? Corrupting some files or deleting all files?
Re: Re: a retelling by Oren JacobDanny ( profile ), 18 May 2012 @ 10:49amIn this case they were not dealing with unknown malware that was steadily erasing the system as they watched. There was, apparently, a delete event at a single point in time that had repercussions that made things disappear while people worked on the movie.
I'll bet things disappeared when whatever editing was being done required a file to be refreshed.
A refresh operation would make the related object disappear when the underlying file was no longer available.
Apart from the set of files that had already been deleted, more files could have been corrupted when the computer was unplugged.
Having said that, this occurred in 1999 when they were probably using the Ext2 filesystem under Linux. These days most everyone uses a filesystem that includes journaling which protects against corruption that may occur when a computer loses power. Ext3 is a journaling filesystem and was introduced in 2001.
In 1998 I had to rebuild my entire home computer system. A power glitch introduced corruption in a Windows 95 system file and use of a Norton recovery tool rendered the entire disk into a handful of unusable files. It took me ten hours to rebuild the OS and re-install all the added hardware, software, and copy personal files from backup floppies. The next day I went out and bought a UPS. Nowadays, sometimes the UPS for one of my computers will fail during one of the three dozen power outages a year I get here. I no longer have problems with that because of journaling.
I've gotta story like this too Ive posted in athe past on Techdirt that I used to work for Ticketmaster. The is an interesting TM story that I don't think ever made it into the public, so I will do it now.aldestrawk ( profile ), 18 May 2012 @ 11:30amBack in the 1980s each TM city was on an independent computer system (PDP unibus systems with RM05 or CDC9766 disk drives. The drives were fixed removable boxes about the size of a washing machine, the removable disk platters about the size of the proverbial breadbox. Each platter held 256mb formatted.
Each city had itts own operations policies, but generally, the systems ran with mirrored drives, the database was backed up every night, archival copies were made monthly. In Chicago, where I worked, we did not have offsite backup in the 1980s. The Bay Area had the most interesting system for offsite backup.
The Bay Area BASS operation, bought by TM in the mid 1980s, had a deal with a taxi driver. They would make their nightly backup copies in house, and make an extra copy on a spare disk platter. Tis cabbie would come by the office about 2am each morning, and they'd put the spare disk platter in his trunk, swapping it for the previous day's copy that had been his truck for 24 hours. So, for the cost of about two platters ($700 at the time) and whatever cash they'd pay the cabbie, they had a mobile offsite copy of their database circulating the Bay Area at all times.
When the World Series earthquake hit in October 1988, the TM office in downtown Oakland was badly damaged. The only copy of the database that survived was the copy in the taxi cab.
That incident led TM corporate to establish much more sophisticated and redundant data redundancy policies.
Re: I've gotta story like this too I like that story. Not that it matters anymore, but taxi cab storage was probably a bad idea. The disks were undoubtedly the "Winchester" type and when powered down the head would be parked on a "landing strip". Still, subjecting these drives to jolts from a taxi riding over bumps in the road could damage the head or cause it to be misaligned. You would have known though it that actually turned out to be a problem. Also, I wouldn't trust a taxi driver with the company database. Although, that is probably due to an unreasonable bias towards cab drivers. I won't mention the numerous arguments with them (not in the U.S.) over fares and the one physical fight with a driver who nearly ran me down while I was walking.Huw Davies , 19 May 2012 @ 1:20amRe: Re: I've gotta story like this too RM05s are removable pack drives. The heads stay in the washing machine size unit - all you remove are the platters.That One Guy ( profile ), 18 May 2012 @ 5:00pmWhat I want to know is this... She copied bits of a movie to her home system... how hard did they have to pull in the leashes to keep Disney's lawyers from suing her to infinity and beyond after she admitted she'd done so(never mind the fact that he doing so saved them apparently years of work...)?Lance , 3 May 2014 @ 8:53am
http://thenextweb.com/media/2012/05/21/how-pixars-toy-story-2-was-deleted-twice-once-by-technology-a nd-again-for-its-own-good/
Evidently, the film data only took up 10 GB in those days. Nowhere near TB...
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Nov 07, 2002 | Linux Journal
The dangers of not testing your backup procedures and some common pitfalls to avoid.
Backups. We all know the importance of making a backup of our most important systems. Unfortunately, some of us also know that realizing the importance of performing backups often is a lesson learned the hard way. Everyone has their scary backup stories. Here are mine. Scary Story #1
Like a lot of people, my professional career started out in technical support. In my case, I was part of a help-desk team for a large professional practice. Among other things, we were responsible for performing PC LAN backups for a number of systems used by other departments. For one especially important system, we acquired fancy new tape-backup equipment and a large collection of tapes. A procedure was put in place, and before-you-go-home-at-night backups became a standard. Some months later, a crash brought down the system, and all the data was lost. Shortly thereafter, a call came in for the latest backup tape. It was located and dispatched, and a recovery was attempted. The recovery failed, however, as the tape was blank . A call came in for the next-to-last backup tape. Nervously, it was located and dispatched, and a recovery was attempted. It also failed because this tape also was blank. Amid long silences and pink-slip glares, panic started to set in as the tape from three nights prior was called up. This attempt resulted in a lot of shouting.
All the tapes were then checked, and they were all blank. To add insult to injury, the problem wasn't only that the tapes were blank--they weren't even formatted! The fancy new backup equipment wasn't smart enough to realize the tapes were not formatted, so it allowed them to be used. Note: writing good data to an unformatted tape is never a good idea.
Now, don't get me wrong, the backup procedures themselves were good. The problem was that no one had ever tested the whole process--no one had ever attempted a recovery. Was it no small wonder then that each recovery failed?
For backups to work, you need to do two things: (1) define and implement a good procedure and (2) test that it works.
To this day, I can't fathom how my boss (who had overall responsibility for the backup procedures) managed not to get fired over this incident. And what happened there has always stayed with me.
A Good Solution
When it comes to doing backups on Linux systems, a number of standard tools can help avoid the problems discussed above. Marcel Gagné's excellent book (see Resources) contains a simple yet useful script that not only performs the backup but verifies that things went well. Then, after each backup, the script sends an e-mail to root detailing what occurred.
I'll run through the guts of a modified version of Marcel's script here, to show you how easy this process actually is. This bash script starts by defining the location of a log and an error file. Two mv commands then copy the previous log and error files to allow for the examination of the next-to-last backup (if required):
#! /bin/bash backup_log=/usr/local/.Backups/backup.log backup_err=/usr/local/.Backups/backup.err mv $backup_log $backup_log.old mv $backup_err $backup_err.oldWith the log and error files ready, a few echo commands append messages (note the use of >>) to each of the files. The messages include the current date and time (which is accessed using the back-ticked date command). The cd command then changes to the location of the directory to be backed up. In this example, that directory is /mnt/data, but it could be any location:
echo "Starting backup of /mnt/data: `date`." >> $backup_log echo "Errors reported for backup/verify: `date`." >> $backup_err cd /mnt/dataThe backup then starts, using the tried and true tar command. The -cvf options request the creation of a new archive (c), verbose mode (v) and the name of the file/device to backup to (f). In this example, we backup to /dev/st0, the location of an attached SCSI tape drive:
tar -cvf /dev/st0 . 2>>$backup_errAny errors produced by this command are sent to STDERR (standard error). The above command exploits this behaviour by appending anything sent to STDERR to the error file as well (using the 2>> directive).
When the backup completes, the script then rewinds the tape using the mt command, before listing the files on the tape with another tar command (the -t option lists the files in the named archive). This is a simple way of verifying the contents of the tape. As before, we append any errors reported during this tar command to the error file. Additionally, informational messages are added to the log file at appropriate times:
mt -f /dev/st0 rewind echo "Verifying this backup: `date`" >>$backup_log tar -tvf /dev/st0 2>>$backup_err echo "Backup complete: `date`" >>$backup_logTo conclude the script, we concatenate the error file to the log file (with cat ), then e-mail the log file to root (where the -s option to the mail command allows the specification of an appropriate subject line):
cat $backup_err >> $backup_log mail -s "Backup status report for /mnt/data" root < $backup_logAnd there you have it, Marcel's deceptively simple solution to performing a verified backup and e-mailing the results to an interested party. If only we'd had something similar all those years ago.
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Jul 20, 2017 | www.tldp.org
.1.1. Backing up with ``tar'':If you decide to use ``tar'' as your backup solution, you should probably take the time to get to know the various command-line options that are available; type " man tar " for a comprehensive list. You will also need to know how to access the appropriate backup media; although all devices are treated like files in the Unix world, if you are writing to a character device such as a tape, the name of the "file" is the device name itself (eg. `` /dev/nst0 '' for a SCSI-based tape drive).
The following command will perform a backup of your entire Linux system onto the `` /archive/ '' file system, with the exception of the `` /proc/ '' pseudo-filesystem, any mounted file systems in `` /mnt/ '', the `` /archive/ '' file system (no sense backing up our backup sets!), as well as Squid's rather large cache files (which are, in my opinion, a waste of backup media and unnecessary to back up):
tar -zcvpf /archive/full-backup-`date '+%d-%B-%Y'`.tar.gz \ --directory / --exclude=mnt --exclude=proc --exclude=var/spool/squid .Don't be intimidated by the length of the command above! As we break it down into its components, you will see the beauty of this powerful utility.
The above command specifies the options `` z '' (compress; the backup data will be compressed with ``gzip''), `` c '' (create; an archive file is begin created), `` v '' (verbose; display a list of files as they get backed up), `` p '' (preserve permissions; file protection information will be "remembered" so they can be restored). The `` f '' (file) option states that the very next argument will be the name of the archive file (or device) being written. Notice how a filename which contains the current date is derived, simply by enclosing the ``date'' command between two back-quote characters. A common naming convention is to add a `` tar '' suffix for non-compressed archives, and a `` tar.gz '' suffix for compressed ones.
The `` --directory '' option tells tar to first switch to the following directory path (the `` / '' directory in this example) prior to starting the backup. The `` --exclude '' options tell tar not to bother backing up the specified directories or files. Finally, the `` . '' character tells tar that it should back up everything in the current directory.
Note: Note: It is important to realize that the options to tar are cAsE-sEnSiTiVe! In addition, most of the options can be specified as either single mneumonic characters (eg. ``f''), or by their easier-to-memorize full option names (eg. ``file''). The mneumonic representations are identified by prefixing them with a ``-'' character, while the full names are prefixed with two such characters. Again, see the "man" pages for information on using tar.
Another example, this time writing only the specified file systems (as opposed to writing them all with exceptions as demonstrated in the example above) onto a SCSI tape drive follows:
tar -cvpf /dev/nst0 --label="Backup set created on `date '+%d-%B-%Y'`." \ --directory / --exclude=var/spool/ etc home usr/local var/spoolIn the above command, notice that the `` z '' (compress) option is not used. I strongly recommend against writing compressed data to tape, because if data on a portion of the tape becomes corrupted, you will lose your entire backup set! However, archive files stored without compression have a very high recoverability for non-affected files, even if portions of the tape archive are corrupted.
Because the tape drive is a character device, it is not possible to specify an actual file name. Therefore, the file name used as an argument to tar is simply the name of the device, `` /dev/nst0 '', the first tape device on the SCSI bus.
Note: Note: The `` /dev/nst0 '' device does not rewind after the backup set is written; therefore it is possible to write multiple sets on one tape. (You may also refer to the device as `` /dev/st0 '', in which case the tape is automatically rewound after the backup set is written.)
Since we aren't able to specify a filename for the backup set, the `` --label '' option can be used to write some information about the backup set into the archive file itself.
Finally, only the files contained in the `` /etc/ '', `` /home/ '', `` /usr/local '', and `` /var/spool/ '' (with the exception of Squid's cache data files) are written to the tape.
When working with tapes, you can use the following commands to rewind, and then eject your tape:
Tip: Tip: You will notice that leading `` / '' (slash) characters are stripped by tar when an archive file is created. This is tar's default mode of operation, and it is intended to protect you from overwriting critical files with older versions of those files, should you mistakenly recover the wrong file(s) in a restore operation. If you really dislike this behavior (remember, its a feature !) you can specify the `` --absolute-paths '' option to tar, which will preserve the leading slashes. However, I don't recommend doing so, as it is Dangerous !
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Aug 26, 2010 | www.linuxjournal.com
One of the most common programs on Linux systems for packaging files is the venerable tar. tar is short for tape archive, and originally, it would archive your files to a tape device. Now, you're more likely to use a file to make your archive. To use a tarfile, use the command-line option -f . To create a new tarfile, use the command-line option -c. To extract files from a tarfile, use the option -x. You also can compress the resulting tarfile via two methods. To use bzip2, use the -j option, or for gzip, use the -z option.
Instead of using a tarfile, you can output your tarfile to stdout or input your tarfile from stdin by using a hyphen (-). With these options, you can tar up a directory and all of its subdirectories by using:
tar cf archive.tar dirThen, extract it in another directory with:
tar xf archive.tarWhen creating a tarfile, you can assign a volume name with the option -V . You can move an entire directory structure with tar by executing:
tar cf - dir1 | (cd dir2; tar xf -)You can go even farther and move an entire directory structure over the network by executing:
tar cf - dir1 | ssh remote_host "( cd /path/to/dir2; tar xf - )"GNU tar includes an option that lets you skip the cd part, -C /path/to/dest. You also can interact with tarfiles over the network by including a host part to the tarfile name. For example:
tar cvf username@remotehost:/path/to/dest/archive.tar dir1This is done by using rsh as the communication mechanism. If you want to use something else, like ssh, use the command-line option --rsh-command CMD. Sometimes, you also may need to give the path to the rmt executable on the remote host. On some hosts, it won't be in the default location /usr/sbin/rmt. So, all together, this would look like:
tar -c -v --rsh-command ssh --rmt-command /sbin/rmt ↪-f username@host:/path/to/dest/archive.tar dir1Although tar originally used to write its archive to a tape drive, it can be used to write to any device. For example, if you want to get a dump of your current filesystem to a secondary hard drive, use:
tar -cvzf /dev/hdd /Of course, you need to run the above command as root. If you are writing your tarfile to a device that is too small, you can tell tar to do a multivolume archive with the -M option. For those of you who are old enough to remember floppy disks, you can back up your home directory to a series of floppy disks by executing:
tar -cvMf /dev/fd0 $HOMEIf you are doing backups, you may want to preserve the file permissions. You can do this with the -p option. If you have symlinked files on your filesystem, you can dereference the symlinks with the -h option. This tells tar actually to dump the file that the symlink points to, not just the symlink.
Along the same lines, if you have several filesystems mounted, you can tell tar to stick to only one filesystem with the option -l. Hopefully, this gives you lots of ideas for ways to archive your files.
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Feb 04, 2017 | superuser.com
linux - Undo tar file extraction mess - Super User
first try to issue
tar tf archivetar will list the contents line by line.This can be piped to
xargsdirectly, but beware : do the deletion very carefully. You don't want to just rm -r everything that tar tf tells you, since it might include directories that were not empty before unpacking!You could do
tar tf archive.tar | xargs -d'\n' rm -v tar tf archive.tar | sort -r | xargs -d'\n' rmdir -vto first remove all files that were in the archive, and then the directories that are left empty.
sort -r(glennjackman suggestedtacinstead ofsort -rin the comments to the accepted answer, which also works sincetar's output is regular enough) is needed to delete the deepest directories first; otherwise a case wheredir1contains a single empty directorydir2will leavedir1after thermdirpass, since it was not empty beforedir2was removed.This will generate a lot of
rm: cannot remove `dir/': Is a directoryand
rmdir: failed to remove `dir/': Directory not empty
rmdir: failed to remove `file': Not a directoryShut this up with
2>/dev/nullif it annoys you, but I'd prefer to keep as much information on the process as possible.And don't do it until you are sure that you match the right files. And perhaps try
rm -ito confirm everything. And have backups, eat your breakfast, brush your teeth, etc.===
List the contents of the tar file like so:
tar tzf myarchive.tarThen, delete those file names by iterating over that list:
while IFS= read -r file; do echo "$file"; done < <(tar tzf myarchive.tar.gz)This will still just list the files that would be deleted. Replace echo with rm if you're really sure these are the ones you want to remove. And maybe make a backup to be sure.
In a second pass, remove the directories that are left over:
while IFS= read -r file; do rmdir "$file"; done < <(tar tzf myarchive.tar.gz)This prevents directories with from being deleted if they already existed before.
Another nice trick by @glennjackman, which preserves the order of files, starting from the deepest ones. Again, remove echo when done.
tar tvf myarchive.tar | tac | xargs -d'\n' echo rmThis could then be followed by the normal rmdir cleanup.
Here's a possibility that will take the extracted files and move them to a subdirectory, cleaning up your main folder.#!/usr/bin/perl -w use strict ; use Getopt :: Long ; my $clean_folder = "clean" ; my $DRY_RUN ; die "Usage: $0 [--dry] [--clean=dir-name]\n" if ( ! GetOptions ( "dry!" => \$DRY_RUN , "clean=s" => \$clean_folder )); # Protect the 'clean_folder' string from shell substitution $clean_folder =~ s / '/' \\ '' / g ; # Process the "tar tv" listing and output a shell script. print "#!/bin/sh\n" if ( ! $DRY_RUN ); while (<>) { chomp ; # Strip out permissions string and the directory entry from the 'tar' list my $perms = substr ( $_ , 0 , 10 ); my $dirent = substr ( $_ , 48 ); # Drop entries that are in subdirectories next if ( $dirent =~ m :/.: ); # If we're in "dry run" mode, just list the permissions and the directory # entries. # if ( $DRY_RUN ) { print "$perms|$dirent\n" ; next ; } # Emit the shell code to clean up the folder $dirent =~ s / '/' \\ '' / g ; print "mv -i '$dirent' '$clean_folder'/.\n" ; }Save this to the file
fix-tar.pland then execute it like this:$ tar tvf myarchive . tar | perl fix - tar . pl -- dryThis will confirm that your
tarlist is like mine. You should get output like:- rw - rw - r --| batch - rw - rw - r --| book - report . png - rwx ------| CaseReports . png - rw - rw - r --| caseTree . png - rw - rw - r --| tree . png drwxrwxr - x | sample /If that looks good, then run it again like this:
$ mkdir cleanup $ tar tvf myarchive . tar | perl fix - tar . pl -- clean = cleanup > fixup . shThe
fixup.shscript will be the shell commands that will move the top-level files and directories into a "clean" folder (in this instance, the folder calledcleanup). Have a peek through this script to confirm that it's all kosher. If it is, you can now clean up your mess with:$ sh fixup . shI prefer this kind of cleanup because it doesn't destroy anything that isn't already destroyed by being overwritten by that initial
tar xv.Note: if that initial dry run output doesn't look right, you should be able to fiddle with the numbers in the two
substrfunction calls until they look proper. The$permsvariable is used only for the dry run so really only the$direntsubstring needs to be proper.One other thing: you may need to use the
taroption--numeric-ownerif the user names and/or group names in thetarlisting make the names start in an unpredictable column.One other thing: you may need to use the
===taroption--numeric-ownerif the user names and/or group names in thetarlisting make the names start in an unpredictable column.That kind of (antisocial) archive is called a tar bomb because of what it does. Once one of these "explodes" on you, the solutions in the other answers are way better than what I would have suggested.
The best "solution", however, is to prevent the problem in the first place.
The easiest (laziest) way to do that is to always unpack a tar archive into an empty directory. If it includes a top level directory, then you just move that to the desired destination. If not, then just rename your working directory (the one that was empty) and move that to the desired location.
If you just want to get it right the first time, you can run tar -tvf archive-file.tar | less and it will list the contents of the archive so you can see how it is structured and then do what is necessary to extract it to the desired location to start with.
The t option also comes in handy if you want to inspect the contents of an archive just to see if it has something you're looking for in it. If it does, you can, optionally, just extract the file(s) you want.
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www.unix.com
Q:A:tar -cjpf /backup /bin /etc /home /opt /root /sbin /usr /var /boot
When i include the / directory it also tar's the /lib /sys /proc /dev filesystems too (and more but these seem to be problem directories.)
Although i have never tried to restore the /sys /proc and /dev directories I have not seen anyone mention that your cant restore /lib but when i tried the server crashed and would not even start the kernel (not even in single user mode).
Can anyone let me know why this happened and provide a more comprehensive list of directories than the 4 mentioned as to what should and shouldn't be backed up and restored? Or point me to a useful site that might explain why you should or shouldn't backup each one?
There's no point in backing-up things like /proc because that's the dynamic handling of processes and memory working sets (virtual memory).However, directories like /lib, although problematic to restore on a running system, you would definitely need them in a disaster recovery situation. You would restore /lib to hard disk in single user or cd boot mode.
So you need to backup all non-process, non-memory files for the backup to be sufficient to recover. It doesn't mean, however, that you should attempt to restore them on a running (multi-user) system.
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www.gnu.org
The `-C' option allows to avoid using subshells:
$ tar -C sourcedir -cf - . | tar -C targetdir -xpf -
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serverfault.com
Antonio Alimba Jun 9 '14 at 13:01
How can i restore from a backup.tgz file generated from another linux server on my own server? I tried the command the following command:
tar xvpfz backup.tgz -C /The above command worked, but it replaced the existing system files which made my linux server not to work properly.
How can i restore without running into trouble?
You can use --skip-old-files command to tell tar not to overwrite existing files.
You could still run into problem with the backup files, if the software versions are different between the two servers. Some data file structure changes might have happened, and things might stop working.
A more refined backup process should be developed.
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# save everything except /mnt and /proc. time tar cfpPzf $TARBALL --directory=/ --one-file-system -xattrs \ --exclude /mnt --exclude /procWhere:
- c - create a new backup archive.
- -C, --directory=DIR
- change to directory DIR
- v - verbose mode, tar will print what it's doing to the screen.
- p - preserves the permissions of the files put in the archive for restoration later.
- P creates absolute names
- z - compress the backup file with 'gzip' to make it smaller.
- f <filename> - specifies where to store the backup, backup.tar.gz is the filename used in this example. It will be stored in the current working directory, the one you set when you used the cd command.
- --xattrs
- Save the user/root xattrs to the archive
- --exclude=/example/path - The options following this model instruct tar what directories NOT to backup. We don't want to backup everything since some directories aren't very useful to include. The first exclusion rule directs tar not to back itself up, this is important to avoid errors during the operation.
- --one-file-system Available at least from tar 1.15 (RHEL 5) Do not include files on a different filesystem. If you want other filesystems, such as a /home partition, or external media mounted in /media backed up, you either need to back them up separately, or omit this flag. If you do omit this flag, you will need to add several more --exclude= arguments to avoid filesystems you do not want. These would be /proc, /sys, /mnt, /media, /run and /dev directories in root. /proc and /sys are virtual filesystems that provide windows into variables of the running kernel, so you do not want to try and backup or restore them. /dev is a tmpfs whose contents are created and deleted dynamically by udev, so you also do not want to backup or restore it. Likewise, /run is a tmpfs that holds variables about the running system that do not need backed up.
- It is important to note that these exclusions are recursive. This means that all folders located within the one excluded will be ignored as well. In the example, excluding the /media folder excludes all mounted drives and media there.
Warning: Exclude actuallyally is condired to be a simple regex expression
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Extract tar.bz2/bzip archivesFiles with extension bz2 are compressed with the bzip algorithm and tar command can deal with them as well. Use the j option instead of the z option.
$ tar -xvjf archivefile.tar.bz2
2. Extract files to a specific directory or path
To extract out the files to a specific directory, specify the path using the "-C" option. Note that its a capital C.
$ tar -xvzf abc.tar.gz -C /opt/folder/However first make sure that the destination directory exists, since tar is not going to create the directory for you and will fail if it does not exist.
3. Extract a single file
To extract a single file out of an archive just add the file name after the command like this
$ tar -xz -f abc.tar.gz "./new/abc.txt"More than once file can be specified in the above command like this
$ tar -xv -f abc.tar.gz "./new/cde.txt" "./new/abc.txt"
4. Extract multiple files using wildcards
Wildcards can be used to extract out a bunch of files matching the given wildcards. For example all files with ".txt" extension.
$ tar -xv -f abc.tar.gz --wildcards "*.txt"
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tardiff.tar.gz v2.1.4 (41,334 bytes)"tardiff" is a Perl script used to quickly make a tarball of changes between versions of an archive, or between pre- and post-build of an application. There are many, many other possible uses.
More complete documentation is now available here.
Some documentation for applying patches of various sorts is now available here.
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Stack Overflow
tarsum is almost what you need. Take its output, run it through sort to get the ordering identical on each, and then compare the two with diff. That should get you a basic implementation going, and it would be easily enough to pull those steps into the main program by modifying the Python code to do the whole job.
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if you try to expand tar file in some production directory you accidentally can overwrite and change ownership of such directories and then spend a lot of type restored status quo. It is safer to expand such tar files in /tmp first and only after that seeing the results then decide whether to copy some directories of re-expand the tar file. Now in production directory.
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Sometimes directories are very similar, for example numbered directories created by some application such as task0001, task0002, ... task0256. In this case you can well perform operation on a wrong directory. For example send to tech support a tar file with the directory that instead of test data contain production run.
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Viktor Balogh's HP-UX blog
This is how to tar a bunch of files and send it over network to another machine over SSH, in one turn:
# cd /etc; tar cf - passwd | ssh hp01a01.w1 "cd /root;tar xf - passwd"Note that with tar you must always use relative path, anyway the files on the target system will be extracted with fullpath and the original files will be overwritten. GNU tar also offers some options which allow the user to modify/transform the paths when files are extracted. You can find the GNU tar on HP-UX under the name gtar, you can download it from the HP-UX porting center:
# which gtar /usr/local/bin/gtarIf you have a 'tar' archive that was made with absolute paths, use 'pax' to extract it to a different directory:
# pax -r -s '|/tmp/|/opt/|' -f test.tarIf you unpack this archive with other user privileges (non-root) all uid and gid will be replaced with the uid and gid from this user. Keep that in mind, if you make backups/restore, practically always do any backup/restore with UID 0.
The use of tar with find isn't apt to work if there are lots of files. Instead use pax(1):
# find . -atime +7 | pax -w | gzip > backup.tgz
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Splitting big files into pieces is a common task. Another common task is to create a tar archive, and split it into smaller chunks that can be burned onto CD/DVD. The straightforward approach is to create the archive and then use 'split.' To do this, you will need more free space on your disk. In fact, you'll need space twice the size of the created archive. To avoid this limitation, split the archive as it is being created.
To create a tar archive that splits itself on the fly use the following set of commands:
First create the archive:
tar -czf /dev/stdout $(DIRECTORY_OR_FILE_TO_COMPRESS) | split -d -b $(CHUNK_SIZE_IN_BYTES) - $(FILE_NAME_PREFIX)To extract the contents:
cat $(FILE_NAME_PREFIX)* >> /dev/stdout | tar -xzf /dev/stdinThe above shown set of commands works on the fly. You don't need additional free space for temporary files.
A few notes about this exercise:
- 'tar -L' prompts you on every chunk created. Compression can not be used with -L option. The above command is not interactive and does not prompt for anything. Compression can be used.
- The number of separate files is 100. This is because we use numerical suffixes – 'split -d.' If the specified chunk size is small you will get 'split: Output file suffixes exhausted' error. Try with bigger chunk size or with alphabetic suffixes.
- 'cat' will concatenate the files properly if they are not renamed. This is due to the fact that the sort order is retained by the appended chunk suffixes.
- Replace 'tar -z' with 'tar -j' for bzip2 compression or try your favourite compression program. Almost all 'tar' and 'split' options should be possible.
- The resulting chunk files are not valid tar archives. They can not be extracted separately. If you want such functionality use 'split-tar,' which also needs more free space.
The information provided in this article is for your information only. The origin of this information may be internal or external to Red Hat. While Red Hat attempts to verify the validity of this information before it is posted, Red Hat makes no express or implied claims to its validity.
vsego:
Isn't it easier to just omit the "f"?
tar cz $(DIRECTORY_OR_FILE_TO_COMPRESS) | split -d -b $(CHUNK_SIZE_IN_BYTES) – $(FILE_NAME_PREFIX)
cat $(FILE_NAME_PREFIX)* | tar xzAlexander Todorov:
You are right. Using /dev/stdin and /dev/stdout is to be more clear.
- Klaus Lichtenwalder says:
December 14th, 2007 at 2:49 pmJust a few nitbits… If you want to use stdin/stdout with tar, it's simply a -
e.g.: tar cf – . | (cd /elsewhere; tar xf -)cat always appends its arguments to stdout, so
cat $(prefix)* | command
is sufficient. I don't know and (honestly) don't care if gnu-tar sends its output to stdout if no f argument given, every other unix uses the default tape device (which is /dev/rmt) if no f argument given (I have to work with Solaris and AIX too…).
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To backup to multiple tape use the following command (backup /home file system):
# tar -clpMzvf /dev/st0 /homeTo compare tape backup, enter:
# tar -dlpMzvf /dev/st0 /homeTo restore tape in case of data loss or hard disk failure:
# tar -xlpMzvf /dev/st0 /homeWhere,
- d : find differences between archive and file system
- x : extract files from an archive
- l : list the contents of an archive
- p : ignore umask when extracting files
- M : create/list/extract multi-volume archive (multiple tapes)
- z : Compress backup using gzip
- v : verbosely list files processed
- f /dev/st0 : Tape device name
- /home : Backup /home file system
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freshmeat.net
Changes: This release adds support for xz compression (with the --xz option) and reassigns the short option -J as a shortcut for --xz. The option -I is now a shortcut for --use-compress-program,... and the --no-recursive option works with --incremental
Changes: This release adds new options: --lzop, --no-auto-compress, and --no-null. It has compressed format recognition and VCS support (--exclude-vcs). It fixes the --null option and... fixes record size autodetection
Changes: This release has new options: -a (selects a compression algorithm basing on the suffix of the archive file name), --lzma (selects the LZMA compression algorithm), and --hard-dereference,... which dereferences hard links during archive creation and stores the files they refer to (instead of creating the usual hard link members)
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Posted: 12 Jun 2002 23:47 PDT
Expires: 19 Jun 2002 23:47 PDT
Question ID: 25116What is the size constraint to "tar" in a UNIX or Linux environment?Subject: Re: UNIX Question! tar size constraint.
Answered By: philip_lynx-ga on 13 Jun 2002 01:05 PDT
Rated:Hi pwharff, The quick answer is: 2^63-1 for the archive, 68'719'476'735 (8^12-1) bytes for each file, if your environment permits that. as I understand your question, you want to know if you can produce tar files that are biger than 2 GBytes (and how big you can really make them). The answer to this question depends on a few simple parameters: 1) Does your operating system support large files? 2) What version of tar are you using? 3) What is the underlying file system? You can answer question 1) for yourself by verifying that your kernel supports 64bit file descriptors. For Linux this is the case for several years now. A quick look in /usr/include/sys/features.h will tell you, if there is any line containing 'FILE_OFFSET_BITS'. If there is, your OS very very probably has support for large files. For Solaris, just check whether 'man largefile' works, or try 'getconf -a|grep LARGEFILE'. If it works, then you have support for large files in the operating system. Again, support for large files has been there for several years. For other operating systems, try "man -k large file', and see what you get -- I'll be gladly providing help if you need to ask for clarification to this answer. Something like "cd /usr/include; grep 'FILE_OFFSET_BITS' * */*" should tell you quickly if there is standard large file support. 2) What version of tar are you using? This is important. Obviously, older tar programs won't be able to handle files or archives that are larger than 2^31-1 bytes (2.1 Gigabytes). Try running 'tar --version'. If the first line indicates you are using gnu tar, then any version newer than 1.12.64 will in principle be able to provide you with large files. Try to run this command: "strings `which tar`|grep 64", and you should see some lines saying lseek64, creat64, fopen64. If yes, your tar contains support for large files. If your tar program does not contain support for large files (most really do, but maybe you are working on a machine older than 1998?), you can download the newest gnu tar from ftp://ftp.gnu.org/pub/gnu/tar and compile it for yourself. The size of files you put into a tar archive (not the archive itself) is limited to 11 octal digits, the max. size of a single file is thus ca. 68 GBytes. 3) Given that both your operating system (and C library), and tar application support large files, the only really limiting factor is the file system that you try to create the file in. The theoretical limit for the tar archive size is 2^63-1 (9'223'372 Terabytes), but you will reach more practical limits (disk or tape size) much quicker. Also take into consideration what the file system is. DOS FAT 12 filesystems don't allow files as big as the Linux EXT2, or Sun UFS file systems. If you need more precise data (for a specific file system type, or for the OS, etc.) please do not hesitate to ask for clarification. I hope my answer is helpful to you, --philip
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Linux Forums
rockytopvolsJust Joined!
Join Date: Sep 2006
Posts: 2ftp tar file size limit?
I am trying to back up my linux box to my windows box's hard drive. To do this I am using the Knoppix distro to boot my linux box. Then I am taring and ftping every file and sending it to my windows box through ftp. (I wanted to tar the files first, so I can preserve permissions) On my windows xp box I am running filezilla's ftp server, and I am transfering to an external external 320Gb NTFS formated hard drive attached to to it through usb. I don't have enough space left on my linux box to tar everything and then transfer, so I am using the following commands:ftp 192.168.1.101 21
binary
put |"tar -cvlO *.*" stuff.tarIt always stops transfering just before 2Gb (1,972,460KB), and the file should be 20Gb or so. What am I doing wrong? Is there some file size limit that I don't know of for ftp or tar? The NTFS files systems should allow bigger files from what I have read. I couldn't find any limit for filezilla. Is this the right place to ask?
Thanks Marsolin
Linux Newbie
rockytopvolsJoin Date: Aug 2006
Posts: 222 I believe NTFS has a 2GB file limitation unless you are running a storage driver with 44-bit LBA support.__________________
Chad
http://linuxappfinder.comJust Joined!
Join Date: Sep 2006
Posts: 2 Everywhere I have read the NTFS limit is in the tens of Terabytes range. I have some files that are bigger than that now.nlsteffens
tar file size limitGenerally, tar can't handle files larger than 2GB. I suggest using an alternative to tar, 'star'. A more comprehensive answer is available here:http://answers.google.com/answers/threadview?id=25116
By the looks of it, gnu tar versions newer than 1.12.64 can handle large files but I can't confirm this.
Regards,
Nick
Alex Stan
Join Date: Aug 2006sbhagatLocation: Hamilton, Ontario
I have a similar problem with big files:I have a 2.2 Gig file on a linux computer. And i mounted Shared Documents(smbfs) from a another(windows) computer. So when i try to copy it it stops at 2 GB. I even tried moving the file in apache, so i can download the file, but apache won't let me.
I can't archive it either.
Is there any way to move that file?
__________________
I like linux!If you are using smbclient, then follow the kbase article:
Regards,
Subodh Bhagat
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ONLamp.com
One last thing about creating archives with
tar:tarwas designed to back up everything in the specified directory. This means that every single file and subdirectory that exists beneath the specified directory will be backed up. It is possible to specify which files you don't want backed up using theXswitch.Let's say I want to backup everything in the
wwwdirectory except for theapache2andzopesubdirectories. In order to use theXswitch, I have to create a file containing the names of the files I wish to exclude. I've found that if you try to create this file using a text editor, it doesn't always work. However, If you create the file usingecho, it does. So I'll make a file calledexclude:echo apache2 > exclude echo zope >> excludeHere, I used the
echocommand to redirect (>) the wordapache2to a new file calledexclude. I then asked it to append (>>) the wordzopeto that same file. If I had forgotten to use two>'s, I would have overwritten the wordapache2with the wordzope.Now that I have a file to use with the
Xswitch, I can make that backup:tar cvfX backup.tar exclude wwwThis is the first backup I've demonstrated where the order of the switches is important. I need to tell
tarthat thefswitch belongs with the wordbackup.tarand theXswitch belongs with the wordexclude. So if I decide to place thefswitch before theXswitch, I need to have the wordbackup.tarbefore the wordexclude.This command will also work as the right switch is still associated with the right word:
tar cvXf exclude backup.tar wwwBut this command would not work the way I want it to:
tar cvfX exclude backup.tar www tar: can't open backup.tar : No such file or directoryHere you'll note that the
Xswitch toldtarto look for a file calledbackup.tarto tell it which files to exclude, which isn't what I meant to telltar.Let's return to the command that did work. To test that it didn't back up the file called
apache2, I usedgrepto sort throughtar's listing:tar tf backup.tar | grep apache2Since I just received my prompt back, I know my exclude file worked. It is interesting to note that since
apache2was really a subdirectory ofwww, all of the files in theapache2subdirectory were also excluded from the backup. I then tested to see if thezopesubdirectory was also excluded in the backup:tar tf backup.tar | grep zope www/zope-zpt/ www/zope-zpt/Makefile www/zope-zpt/distinfo www/zope-zpt/pkg-comment <output snipped>This time I got some information back, as there were other subdirectories that started with the term "zope," but the subdirectory that was just called
zopewas excluded from the backup.Now that we know how to make backups, let's see how we can restore data from a backup. Remember from last week the difference between a relative and an absolute pathname, as this has an impact when you are restoring data. Relative pathnames are considered a good thing in a backup. Fortunately, the
tarutility that comes with your FreeBSD system strips the leading slash, so it will always use a relative pathname -- unless you specifically overrride this default by using thePswitch.It's always a good idea to do a listing of the data in an archive before you try to restore it, especially if you receive a
tararchive from someone else. You want to make sure that the listed files do not begin with "/", as that indicates an absolute pathname. I'll check the first few lines in my backup:tar tf backup.tar | head www/ www/mod_trigger/ www/mod_trigger/Makefile www/mod_trigger/distinfo www/mod_trigger/pkg-comment www/mod_trigger/pkg-descr www/mod_trigger/pkg-plist www/Mosaic/ www/Mosaic/files/ www/Mosaic/files/patch-aiNone of these files begin with a "
/", so I'll be able to restore this backup anywhere I would like. I'll practice a restore by making a directory I'll calltesting, and then I'll restore the entire backup to that directory:mkdir testing cd testing tar xvf ~test/backup.tarYou'll note that I
cd'ed into the directory to contain the restored files, then toldtarto restore or extract the entirebackup.tarfile using thexswitch. Once the restore was complete, I did a listing of the testing directory:ls wwwI then did a listing of that new
wwwdirectory and saw that I had successfully restored the entirewwwdirectory structure, including all of its subdirectories and files.It's also possible to just restore a specific file from the archive. Let's say I only need to restore one file from the
www/chimeradirectory. First, I'll need to know the name of the file, so I'll get a listing fromtarand usegrepto search for the files in thechimerasubdirectory:tar tf backup.tar | grep chimera www/chimera/ www/chimera/files/ www/chimera/files/patch-aa www/chimera/scripts/ www/chimera/scripts/configure www/chimera/pkg-comment www/chimera/Makefile <snip>I'd like to just restore the file
www/chimera/Makefile, and I'd like to restore it to the home directory of the user namedgenisis. First, I'llcdto the directory to which I want that file restored, and then I'll telltarjust to restore that one file:cd ~genisis tar xvf ~test/backup.tar www/chimera/MakefileYou'll note some interesting things if you try this at home. When I did a listing of
genisis' home directory, I didn't see a file calledMakefile, but I did see a directory calledwww. This directory contained a subdirectory calledchimera, which contained a file calledMakefile. Remember, when you make an archive, you are including a directory structure, and when you restore from an archive, you recreate that directory structure.You'll also note that the original ownesship, permissions, and file creation time were also restored with that file:
ls -l ~genisis/www/chimera/Makefile -rw-r--r-- 1 test wheel 406 May 11 09:52 www/chimera/MakefileThat should get you started with using the
tarutility. In next week's article, I'll continue with some of the interesting options that can be used withtar, and then I'll introduce thecpioarchiver.
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The tar program is an archiving program designed to store and extract files from an archive file known as a tarball. A tarball may be made on a tape drive; however, it is also common to write a tarball to a normal file.
If you want to know more options about tar click here
Making backups with tar
A full backup can easily be made with tar:
# tar --create --file /dev/ftape /usr/src
tar: Removing leading / from absolute path names in the archiveThe example above uses the GNU version of tar and its long option names. The traditional version of tar only understands single character options. The GNU version can also handle backups that don't fit on one tape or floppy, and also very long paths; not all traditional versions can do these things. (Linux only uses GNU tar.)
If your backup doesn't fit on one tape, you need to use the --multi-volume (-M) option:
# tar -cMf /dev/fd0H1440 /usr/src
tar: Removing leading / from absolute path names in the archive Prepare volume #2 for /dev/fd0H1440 and hit return:Note that you should format the floppies before you begin the backup, or else use another window or virtual terminal and do it when tar asks for a new floppy.
After you've made a backup, you should check that it is OK, using the --compare (-d) option:
# tar --compare --verbose -f /dev/ftape
usr/src/
usr/src/linux
usr/src/linux-1.2.10-includes/Failing to check a backup means that you will not notice that your backups aren't working until after you've lost the original data.
An incremental backup can be done with tar using the --newer
# tar --create --newer '8 Sep 1995' --file /dev/ftape /usr/src --verbose
tar: Removing leading / from absolute path names in the archive
usr/src/
usr/src/linux-1.2.10-includes/
usr/src/linux-1.2.10-includes/include/
usr/src/linux-1.2.10-includes/include/linux/
usr/src/linux-1.2.10-includes/include/linux/modules/
usr/src/linux-1.2.10-includes/include/asm-generic/
usr/src/linux-1.2.10-includes/include/asm-i386/
usr/src/linux-1.2.10-includes/include/asm-mips/
usr/src/linux-1.2.10-includes/include/asm-alpha/
usr/src/linux-1.2.10-includes/include/asm-m68k/
usr/src/linux-1.2.10-includes/include/asm-sparc/
usr/src/patch-1.2.11.gzUnfortunately, tar can't notice when a file's inode information has changed, for example, that its permission bits have been changed, or when its name has been changed. This can be worked around using find and comparing current filesystem state with lists of files that have been previously backed up. Scripts and programs for doing this can be found on Linux ftp sites.
12.4.2. Restoring files with tar
# tar --extract --same-permissions --verbose --file /dev/fd0H1440
The --extract (-x) option for tar extracts files:
usr/src/
usr/src/linux
usr/src/linux-1.2.10-includes/
usr/src/linux-1.2.10-includes/include/
usr/src/linux-1.2.10-includes/include/linux/
usr/src/linux-1.2.10-includes/include/linux/hdreg.h
usr/src/linux-1.2.10-includes/include/linux/kernel.hYou also extract only specific files or directories (which includes all their files and subdirectories) by naming on the command line:
# tar xpvf /dev/fd0H1440
usr/src/linux-1.2.10-includes/include/linux/hdreg.h
usr/src/linux-1.2.10-includes/include/linux/hdreg.h# tar --list --file /dev/fd0H1440
Use the --list (-t) option, if you just want to see what files are on a backup volume:
usr/src/
usr/src/linux
usr/src/linux-1.2.10-includes/
usr/src/linux-1.2.10-includes/include/
usr/src/linux-1.2.10-includes/include/linux/
usr/src/linux-1.2.10-includes/include/linux/hdreg.h
usr/src/linux-1.2.10-includes/include/linux/kernel.hNote that tar always reads the backup volume sequentially, so for large volumes it is rather slow. It is not possible, however, to use random access database techniques when using a tape drive or some other sequential medium.
tar doesn't handle How-to Using Tar (Taring)
By SuperHornet from http://www.fluidgravity.com/ (http://www.fluidgravity.com/)
Ok well here is a short listing on how to use the command tar to backup you data..
Tar is solely an archiving app. Tar by its self wont compress files.But you say "then what is a .tar.gz"
It's a tar file that has been compressed with a different compression utility. The .gz=gzip is the compression app use to compress it.
Here is tar in its simplest form
tar -cvf filename.tar /path/to/files
- -c means create
- -f means filename (-f should always be last when you using syntax)
- -v Verbose will display all the files its puts in the tar and error you might have incurred
You should see the filename.tar file in what ever directory you ran tar from.
You say "But I want to make the tarball compressed"
Well then -z is the option you want to include in your syntax
tar -zvcf filename.tar.gz /path/to/files
#notice I had to add the .gz extension.
-Z( no not -z) will run it thru the old compress app.Now when I make a tarball I like to keep all the path's from which the file is in.
For this use the -P (absolute path)tar -zPvcf filename.tar.gz /path/to/fileWhen I extract it I will see a new directory called /path
and under that I will see the "to" directory, and the "file" is under "to"Now you say "I want to backup ALL my files in my home directory EXCEPT the temp directory I use". No problem.
tar -zPvcf myhomebackup.tar.gz --exclude /home/erik/temp /home/erik
The --exclude will give you this option, just slip it in between the tar filename and the path your going to backup. This will exclude the whole temp directory.You say "Ok this tar thing is pretty cool but I want to backup only single files from all around the drive.
No problem, this requires a bit more work, but hey this is UNIX, get used to it.
Make a file called locations (call it anything you like). In locations place the full path to each file you want to backup on a new line. Please be aware that you have to have read rights to the files you are going to backup.
/etc/mail/sendmail.cf
/usr/local/apache/conf/httpd.conf
/home/erik/scripts
Now with the -T option I can tell it to use the locations file.tar -zPvcf backup.tar.gz -T locations
Now if you want to backup the whole drive. Then you will have to exclude lots of files like /var/log/* and /usr/local/named/*
Using the -X option you can create an exclude file just like the locations file.
tar -zPvcf fullbackup.tar.gz -X /path/to/excludefile -T /path/to/locationsfile
Now a month has gone by and you need to update your myhomebackup.tar.gz with new or changed files.
This requires a extra step (quit your bitching I already told you why)
You have to uncompress it first but not untar it.gunzip /path/to/myhomebackup.tar.gz
This will leave your myhomebackup.tar.gz mising the .gz.
Now we can update your tarball with -u and then we are going to compress it again.tar -Puvf myhomebackup.tar /home/erik | gzip mybackup.tar
It will add the .gz for you.Tar is a pretty old app and has lots of Fetchers.
I suggest reading the man pages to get a lits of all the options.
I have included a little perl script that I made so I can run it as cron job evernight and get a full backup each time.
It wouldn't be that hard to update the tarball but I just like full backups.
Feel free to use it.If you want to extract the tarball that is compressed
tar -zxvf filename.tar.gz
-x extractIf it is not compressed then
tar -xvf filename.tar
#!/usr/bin/perl
#sysbkup.pl
#Created by Erik Mathis hornet@fluidgravity.com 7/02#Change These paths to fix your needs.
my $filename="/home/sysbkup/backup";
my $exclude="/home/erik/exclude";
my $data="/home/erik/locations";
my $tar="\.tar";
my $gz="\.gz";
$file=$filename.$tar.$gz;system ("tar -Pzcvf $file -X $exclude -T $data");
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Sort of answered my own question. I downloaded and install star:
http://www.fokus.gmd.de/research/cc/glone/employees/joerg.schilling/private/star.html
an enhanced version of tar that includes a name-modification option:
-s replstr
Modify file or archive member names named by a pattern
according to the substitution expression replstr. The
format of replstr is:-s /old/new/[gp]
eks
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- To: LUCI List <luci-discuss@luci.org>
- Subject: Re: Tar question -- star is recommended until GNU Tar 1.14 is
- From: "Bryan J. Smith" <b.j.smith@ieee.org>
- Date: Sat, 07 Aug 2004 01:24:33 -0400
- In-Reply-To: <Pine.LNX.4.44.0408052156230.16610-100000@demeter.museum.state.il.us>
- Organization: Linux Users of Central Illinois
- References: <Pine.LNX.4.44.0408052156230.16610-100000@demeter.museum.state.il.us>
- Reply-To: luci-discuss@luci.org
- Sender: luci-discuss-owner@luci.org
On Thu, 2004-08-05 at 22:58, Erich Schroeder wrote: > Sort of answered my own question. I downloaded and install star: > http://www.fokus.gmd.de/research/cc/glone/employees/joerg.schilling/private/star.html > an enhanced version of tar It's not really an "enhanced version of tar" but a more _POSIX_ compliant version. That's why it has been a part of Fedora Core (FC) since version 0.8* and _recommended_over_ GNU Tar 1.13. Understand that cpio, tar and, their new replacement, pax, just write what is known as "ustar" format. The latest IEEE POSIX 2001 and X/Open Single Unix Specification (SUS) 3 from the "Austin Group" defines a lot of new functionality that really makes up for lack of capability in the older 1988 and subsequent releases until the late '90s drafts. This includes overcoming POSIX 1988+ path/naming limitations, as well as newer POSIX 2001 capabilities like storing POSIX EA/ACLs. In the meanwhile, the GNU maintainers decided to release their own extensions that are not compliant. It was a necessary evil, but now that the POSIX/SUS standard has been updated, it's time for GNU to come around. The current GNU Tar 1.14 alpha adds these capabilities. star actually had EA/ACLs support on Solaris** _before_ the POSIX standardization, so adopting it for POSIX 2001 / SUS 3 ustar meta-data format was easy. Unfortunately POSIX 2001 / SUS 3 still does _not_ address the issue of compression. I hate the idea of block compressing the entire archive, which renders it largely unrecoverable after a single byte error (at least with LZ77/gzip or LZO/lzop -- BWT/bzip2 may be better at recovery though). That's my "beef" with the whole ustar format in general. I would have really liked a flexible per-file compression meta-data tag in the standard. Until then, we have aging cpio replacements like afio. -- Bryan *NOTE: This is the actual "disttag" versioning (i.e., technical reasons) for pre-Fedora Core "community Linux" releases from Red Hat that are now recommended for Fedora Legacy support (i.e., FC 0.8 is fka "RHL" 8), in addition to any relevant trademark (i.e., non-technical) considerations. **NOTE: legacy star used Sun's tar approach -- an ACL "attribute file" preceding the data file, but using the same name. That way if the tar program extracting it was "Sun EA/ACL aware," it would read it, but if not, it would just overwrite the attribute file with the actual when extracted. Quite ingenious of an approach. -- Engineers scoff at me because I have IT certifications IT Pros scoff at me because I am a degreed engineer I see and understand both of their viewpoints Unfortunately Engineers and IT Pros only see in me what they dislike about the other trade ------------------------------------------------------ Bryan J. Smith b.j.smith@ieee.org
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Martin Maney maney at pobox.com
Sun Jun 8 21:25:09 CDT 2003
- Previous message: [LUNI] Incremental Tar
- Next message: [LUNI] Incremental Tar
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
On Sun, Jun 08, 2003 at 05:31:10PM -0500, Patrick R. White wrote: > So isn't this a good reason to use the dump/restore utilities to begin > with?
Maybe, but dump/restore is no panacea. Back in 1991, at LISA V, Elizabeth Zwicky of SRI presented a fascinating paper comparing the performance and problems of then-extant version of tar, cpio, pax, afio, as well as dump.
dump did well on most of the tests, but by its design it is capable of really frighetening errors if the filesystem is not quiesced (in practice, unmounted or mounted r/o would appear to be necessary) during dump. Also worth noting is that dump is quite filesystem-specific, and I seem to recall hearing that the ext2 version was interestingly broken a while ago. Since I don't employ dump, I can't tell you any more than that, sorry.
The only link I can find to the paper is from here:
http://www.phys.washington.edu/~belonis/
There's a postscript file and jpegs of the printed document. I thought there used to be something less cumbersome, but Google isn't finding it for me. It did find a good number of now-dead links, though. :-(
Ah, "zwicky backup torture" is a better search key. Still mostly passing mentions of this seminal work. Here's a more recent survey paper about *nix backup techniques:
http://citeseer.nj.nec.com/chervenak98protecting.html
Here's another useful compendium that seems to be currently maintained
http://www.cybertiggyr.com/gene/htdocs/unix_tape/unix_tape.html
OTOH, "cpio: Some Linux folks appear to use this" seems... odd.
Ah, google-diving!
--
A delicate balance is necessary between sticking with the things you know and can rely upon, and exploring things which have the potential to be better. Assuming that either of these strategies is the one true way is silly. -- Graydon Hoare
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>From: Paul Eggert <eggert@twinsun.com>
>> From: Joey Hess <joey@kitenet.net>
>> Date: Mon, 25 Mar 2002 14:57:20 -0500
>>
>> According to the test suite documentation, POSIX 10.1.1-12(A) says
>> that Fields mode, uid, gid, size, mtime, chksum, devmajor and
>> devminor are leading zero-filled octal numbers in ASCII and are
>> terminated by one or more space or null characters.
>OK, I'll change the behavior of GNU "tar" in a future release.
I am not sure what the text from Joey Hess should be related to...
... his mail did not reach this group.
>From looking at the archives created by GNUtar, I see the following deviations:
- Checksum field repeats a bug found in ancient TAR implementaions.
This seems to be a rudiment from early tests done by John Gilmore
in PD tar where he did try to run "cmp" on PD-tar vs. Sun-tar
archives.
This is a minor deviation and easy to fix.
- The devmajor/devminor fields are missing if the file is not
a block/char device - here we see non left zero filled fields.
A minor deviation that is easy to fix.
- The Magic Version field contains spaces instead of "00".
This is just a proof that GNUtar is not POSIX.1-1990 compliant
and should not be changed before GNUtar has been validated to
create POSIX.1 compliant archives.
...
>conformance by running the "tar" command. A POSIX test suite should
>invoke the "pax" command instead.
While this is the correct answer from theory, you should take into account
that "pax" has not been accepted by a major number of people in the community.
AFAIK, LSB intends to be UNIX-98 compliant, so it would make sense to support
cpio/pax/tar in a way compliant to the SUSv2 document.
Let me comment on the current Linux status. We have:
- GNUcpio which is neither POSIX.1-1990 compliant nor does it allow
to archive files >= 2 GB.
For a list of problems look into:
ftp://ftp.fokus.gmd.de/pub/unix/star/README.otherbugs
- GNUtar which is not POSIX compliant too but supports files >= 2 GB.
Problems with archive exchange with POSIX compliant platforms:
- does not handle long filenames in a POSIX compliant way.
This has become better with recent alpha releases, but
gnutar -tvf archive still does not work at all.
Archives containing long filenames and created with gtar
cannot be read by POSIX (only) tar implementations correctly.
- Is for unknown reason unable to list archives created with other
TAR implementations (e.g. Sun's tar on Solaris or star).
For an example look into:
ftp://ftp.fokus.gmd.de/pub/unix/star/testscripts/README.gtarfail
- Pax (the version fixed by Thorsten Kukuk) is POSIX.1-1990 compliant
but it is not able to handle files >= 2 GB.
as part of commercial Linux distributions. From a standpoint of what people
might like to see, this could be better. A year 2002 POSIX OS should include at
least one program that creates POSIX compliant tar archives _and_ supports
large files.
People who get and compile software themselves may also use "star" which is
POSIX.1-1990 andd POSIX.1-2001 compliant and supports files >= 2 GB.
So why is star missing from Linux distributions?
>Also, I should mention that GNU tar does not generate POSIX-format
>ustar archives, nor does it claim to. Volunteers to fix this
>deficiency would be welcome, but that's a different topic. It is a
>quality-of-implementation issue, and is not strictly a
>POSIX-conformance issue.
There is "star" which is POSIX compliant. A good idea would be to move
gnutar to /bin/gtar on Linux and put star on /bin/star and /bin/tar.
This way, Linux gets a POSIX compliant TAR and users of gnutar will be granted
to have 100% backward compatibility when calling "gtar".
ftp://ftp.fokus.gmd.de/pub/unix/star/aplha/
If you don't like to do the transition too fast, here is an idea for an
intermediate step:
Put star on /bin/star, install the star man page for "star" and "tar" and move
the GNUtar man page to "gtar".
/*--------------------------------------------------------------------------*/
Another topic:
>From a discussion at CeBIT, I am now aware of the fact that LSB did
"standardise" on the GNUtar options at:
http://www.linuxbase.org/spec/gLSB/gLSB/tar.html
Let me comment on this too:
It seems to be a bad idea to standardize TAR options that are incompatible
with POSIX standards. So let me first introduce a list of incompatible options
found in GNUtar. The complete list is in:
ftp://ftp.fokus.gmd.de/pub/unix/star/aplha/STARvsGNUTAR
/*--------------------------------------------------------------------------*/
Gnu tar options that (in the single char variant) are incompatible:
BsS -F, --info-script=FILE run script at end of each tape (implies -M)
s -L, --tape-length=NUM change tape after writing NUM x 1024 bytes
s -M, --multi-volume create/list/extract multi-volume archive
s -O, --to-stdout extract files to standard output
sS (+) -P, --absolute-names don't strip leading `/'s from file names
s -S, --sparse handle sparse files efficiently
s -T, -I, --files-from=NAME get names to extract or create from file NAME
s -U, --unlink-first remove each file prior to extracting over it
s -V, --label=NAME create archive with volume name NAME
s -d, --diff, --compare find differences between archive and file system
sP -l, --one-file-system stay in local file system when creating archive
sP -o, --old-archive, --portability write a V7 format archive
B Incompatible with BSD tar
s Incompatible with star
S Incompatible with Sun's/SVr4 tar
P Incompatible with POSIX
+) This option is the only option where star deviates from other tar
implementations, but as there is no other nice way to have an option to
specify that the last record should be partial and the star option -/
is easy to remember as well as -P for Partial record is I see no need
to change star.
/*--------------------------------------------------------------------------*/
Please note that all these incompatibilities are "against" other TAR
implementations that are much older than GNUtar. As as example, let me use the
-M (do not cross mount points) option in star which is available since 1985.
It looks inapropriate to me to include single char options from GNUtar that are not
found in other tar implementations into something like LSB.
To avoid LSB systems to break POSIX.1-1990 and SVSv2, I would recommend to
change http://www.linuxbase.org/spec/gLSB/gLSB/tar.html so that the following
single char options will disappear (oder is the order from the web page):
-A This option has low importance and there is no need to have a single
char option for it.
-d (*) Use by star with different semantic, the short option should not
1be in the LSB standard.
-F (*) Used with a different semantic by BSD tar for a long time
the short option should not be in the LSB standard.
-G The short option should not be in the LSB standard.
-g The short option should not be in the LSB standard.
-K The short option should not be in the LSB standard.
-l This option violates the POSIX/SUSv2 semantics, it needs to be removed
from the LSB standard.
-L (*) The short option should not be in the LSB standard.
-M (*) The short option should not be in the LSB standard.
-N The short option should not be in the LSB standard.
-o This option violates the POSIX/SUSv2 semantics, it needs to be removed
from the LSB standard.
-O (*) The short option should not be in the LSB standard.
-P (*) The short option should not be in the LSB standard.
-R The short option should not be in the LSB standard.
-s The short option should not be in the LSB standard.
-S (*) The short option should not be in the LSB standard.
-T (*) The short option should not be in the LSB standard.
-V (*) The short option should not be in the LSB standard.
-W The short option should not be in the LSB standard.
*) Used by one or more other TAR implementations with different semantics
so defining it in LSB creates problems.
Jörg
EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
js@cs.tu-berlin.de (uni) If you don't have iso-8859-1
schilling@fokus.gmd.de (work) chars I am J"org Schilling
URL: http://www.fokus.gmd.de/usr/schilling ftp://ftp.fokus.gmd.de/pub/unix
--
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with subject of "unsubscribe". Trouble? Email listmaster@lists.linuxbase.org
Google matched content |
...
Full system backup with tar - ArchWiki
How to properly backup your system using TAR
Solaris 9 tar manpage - Solaris tar understands ACLs, but GNU tar don't
(gnu)tar - GNU version of tar archiving utility
Linux and Solaris ACLs - Backup
The Star tape archiver by Jörg Schilling, available at ftp://ftp.berlios.de/pub/star/, since version 1.4a07 supports backing up and restoring of POSIX Access Control Lists. For best results, it is recommended to use a recent star-1.5 version. Star is compatible with SUSv2 tar (UNIX-98 tar), understands the GNU tar archive extensions, and can generate pax archives.
- -A, --catenate, --concatenate
- append tar files to an archive
- -c, --create
- create a new archive
- -d, --diff, --compare
- find differences between archive and file system
- -r, --append
- append files to the end of an archive
- -t, --list
- list the contents of an archive
- -u, --update
- only append files that are newer than the existing in archive
- -x, --extract, --get
- extract files from an archive
- --delete
- delete from the archive (not for use on mag tapes!)
- --atime-preserve
- don't change access times on dumped files
- -b, --blocking-factor N
- block size of Nx512 bytes (default N=20)
- -B, --read-full-blocks
- reblock as we read (for reading 4.2BSD pipes)
- --backup BACKUP-TYPE
- backup files instead of deleting them using BACKUP-TYPE simple or numbered
- --block-compress
- block the output of compression program for tapes
- -C, --directory DIR
- change to directory DIR
- --check-links
- warn if number of hard links to the file on the filesystem mismatch the number of links recorded in the archive
- --checkpoint
- print directory names while reading the archive
- -f, --file [HOSTNAME:]F
- use archive file or device F (default "-", meaning stdin/stdout)
- -F, --info-script F --new-volume-script F
- run script at end of each tape (implies --multi-volume)
- --force-local
- archive file is local even if has a colon
- --format FORMAT
- selects output archive format
v7 - Unix V7 oldgnu - GNU tar <=1.12 gnu - GNU tar 1.13 ustar - POSIX.1-1988 posix - POSIX.1-2001- -g, --listed-incremental F
- create/list/extract new GNU-format incremental backup
- -G, --incremental
- create/list/extract old GNU-format incremental backup
- -h, --dereference
- don't dump symlinks; dump the files they point to
- --help
- like this manpage, but not as cool
- -i, --ignore-zeros
- ignore blocks of zeros in archive (normally mean EOF)
- --ignore-case
- ignore case when excluding files
- --ignore-failed-read
- don't exit with non-zero status on unreadable files
- --index-file FILE
- send verbose output to FILE instead of stdout
- -j, --bzip2
- filter archive through bzip2, use to decompress .bz2 files
- -k, --keep-old-files
- keep existing files; don't overwrite them from archive
- -K, --starting-file F
- begin at file F in the archive
- --keep-newer-files
- do not overwrite files which are newer than the archive
- -l, --one-file-system
- stay in local file system when creating an archive
- -L, --tape-length N
- change tapes after writing N*1024 bytes
- -m, --touch, --modification-time
- don't extract file modified time
- -M, --multi-volume
- create/list/extract multi-volume archive
- --mode PERMISSIONS
- apply PERMISSIONS while adding files (see chmod(1))
- -N, --after-date DATE, --newer DATE
- only store files newer than DATE
- --newer-mtime DATE
- like --newer, but with a DATE
- --no-anchored
- match any subsequenceof the name's components with --exclude
- --no-ignore-case
- use case-sensitive matching with --exclude
- --no-recursion
- don't recurse into directories
- --no-same-permissions
- apply user's umask when extracting files instead of recorded permissions
- --no-wildcards
- don't use wildcards with --exclude
- --no-wildcards-match-slash
- wildcards do not match slashes (/) with --exclude
- --null
- --files-from reads null-terminated names, disable --directory
- --numeric-owner
- always use numbers for user/group names
- -o, --old-archive, --portability
- like --format=v7; -o exhibits this behavior when creating an archive (deprecated behavior)
- -o, --no-same-owner
- do not attempt to restore ownesship when extracting; -o exhibits this behavior when extracting an archive
- -O, --to-stdout
- extract files to standard output
- --occurrence NUM
- process only NUM occurrences of each named file; used with --delete, --diff, --extract, or --list
- --overwrite
- overwrite existing files and directory metadata when extracting
- --overwrite-dir
- overwrite directory metadata when extracting
- --owner USER
- change owner of extraced files to USER
- -p, --same-permissions, --preserve-permissions
- extract all protection information
- -P, --absolute-names
- don't strip leading '/'s from file names
- --pax-option KEYWORD-LIST
- used only with POSIX.1-2001 archives to modify the way tar handles extended header keywords
- --posix
- like --format=posix
- --preserve
- like --preserve-permissions --same-order
- --acls
- this option causes tar to store each file's ACLs in the archive.
- --selinux
- this option causes tar to store each file's SELinux security context information in the archive.
- --xattrs
- this option causes tar to store each file's extended attributes in the archive. This option also enables --acls and--selinux if they haven't been set already, due to the fact that the data for those are stored in special xattrs.
- --no-acls
- This option causes tar not to store each file's ACLs in the archive and not to extract any ACL information in an archive.
- --no-selinux
- this option causes tar not to store each file's SELinux security context information in the archive and not to extract any SELinux information in an archive.
- --no-xattrs
- this option causes tar not to store each file's extended attributes in the archive and not to extract any extended attributes in an archive. This option also enables --no-acls and --no-selinux if they haven't been set already.
- -R, --record-number
- show record number within archive with each message
- --record-size SIZE
- use SIZE bytes per record when accessing archives
- --recursion
- recurse into directories
- --recursive-unlink
- remove existing directories before extracting directories of the same name
- --remove-files
- remove files after adding them to the archive
- --rmt-command CMD
- use CMD instead of the default /usr/sbin/rmt
- --ssh-command CMD
- use remote CMD instead of ssh(1)
- -s, --same-order, --preserve-order
- list of names to extract is sorted to match archive
- -S, --sparse
- handle sparse files efficiently
- --same-owner
- create extracted files with the same ownesship
- --show-defaults
- display the default options used by tar
- --show-omitted-dirs
- print directories tar skips while operating on an archive
- --strip-components NUMBER, --strip-path NUMBER
- strip NUMBER of leading
components from file names before extraction
(1) tar-1.14 uses --strip-path, tar-1.14.90+ uses --strip-components
- --suffix SUFFIX
- use SUFFIX instead of default '~' when backing up files
- -T, --files-from F
- get names to extract or create from file F
- --totals
- print total bytes written with --create
- -U, --unlink-first
- remove existing files before extracting files of the same name
- --use-compress-program PROG
- access the archive through PROG which is generally a compression program
- --utc
- display file modification dates in UTC
- -v, --verbose
- verbosely list files processed
- -V, --label NAME
- create archive with volume name NAME
- --version
- print tar program version number
- --volno-file F
- keep track of which volume of a multi-volume archive its working in FILE; used with --multi-volume
- -w, --interactive, --confirmation
- ask for confirmation for every action
- -W, --verify
- attempt to verify the archive after writing it
- --wildcards
- use wildcards with --exclude
- --wildcards-match-slash
- wildcards match slashes (/) with --exclude
- --exclude PATTERN
- exclude files based upon PATTERN
- -X, --exclude-from FILE
- exclude files listed in FILE
- -Z, --compress, --uncompress
- filter the archive through compress
- -z, --gzip, --gunzip, --ungzip
- filter the archive through gzip
- --use-compress-program PROG
- filter the archive through PROG (which must accept -d)
- -[0-7][lmh]
- specify drive and density
Society
Groupthink : Two Party System as Polyarchy : Corruption of Regulators : Bureaucracies : Understanding Micromanagers and Control Freaks : Toxic Managers : Harvard Mafia : Diplomatic Communication : Surviving a Bad Performance Review : Insufficient Retirement Funds as Immanent Problem of Neoliberal Regime : PseudoScience : Who Rules America : Neoliberalism : The Iron Law of Oligarchy : Libertarian Philosophy
Quotes
War and Peace : Skeptical Finance : John Kenneth Galbraith :Talleyrand : Oscar Wilde : Otto Von Bismarck : Keynes : George Carlin : Skeptics : Propaganda : SE quotes : Language Design and Programming Quotes : Random IT-related quotes : Somerset Maugham : Marcus Aurelius : Kurt Vonnegut : Eric Hoffer : Winston Churchill : Napoleon Bonaparte : Ambrose Bierce : Bernard Shaw : Mark Twain Quotes
Bulletin:
Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks The efficient markets hypothesis : Political Skeptic Bulletin, 2013 : Unemployment Bulletin, 2010 : Vol 23, No.10 (October, 2011) An observation about corporate security departments : Slightly Skeptical Euromaydan Chronicles, June 2014 : Greenspan legacy bulletin, 2008 : Vol 25, No.10 (October, 2013) Cryptolocker Trojan (Win32/Crilock.A) : Vol 25, No.08 (August, 2013) Cloud providers as intelligence collection hubs : Financial Humor Bulletin, 2010 : Inequality Bulletin, 2009 : Financial Humor Bulletin, 2008 : Copyleft Problems Bulletin, 2004 : Financial Humor Bulletin, 2011 : Energy Bulletin, 2010 : Malware Protection Bulletin, 2010 : Vol 26, No.1 (January, 2013) Object-Oriented Cult : Political Skeptic Bulletin, 2011 : Vol 23, No.11 (November, 2011) Softpanorama classification of sysadmin horror stories : Vol 25, No.05 (May, 2013) Corporate bullshit as a communication method : Vol 25, No.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law
History:
Fifty glorious years (1950-2000): the triumph of the US computer engineering : Donald Knuth : TAoCP and its Influence of Computer Science : Richard Stallman : Linus Torvalds : Larry Wall : John K. Ousterhout : CTSS : Multix OS Unix History : Unix shell history : VI editor : History of pipes concept : Solaris : MS DOS : Programming Languages History : PL/1 : Simula 67 : C : History of GCC development : Scripting Languages : Perl history : OS History : Mail : DNS : SSH : CPU Instruction Sets : SPARC systems 1987-2006 : Norton Commander : Norton Utilities : Norton Ghost : Frontpage history : Malware Defense History : GNU Screen : OSS early history
Classic books:
The Peter Principle : Parkinson Law : 1984 : The Mythical Man-Month : How to Solve It by George Polya : The Art of Computer Programming : The Elements of Programming Style : The Unix Hater’s Handbook : The Jargon file : The True Believer : Programming Pearls : The Good Soldier Svejk : The Power Elite
Most popular humor pages:
Manifest of the Softpanorama IT Slacker Society : Ten Commandments of the IT Slackers Society : Computer Humor Collection : BSD Logo Story : The Cuckoo's Egg : IT Slang : C++ Humor : ARE YOU A BBS ADDICT? : The Perl Purity Test : Object oriented programmers of all nations : Financial Humor : Financial Humor Bulletin, 2008 : Financial Humor Bulletin, 2010 : The Most Comprehensive Collection of Editor-related Humor : Programming Language Humor : Goldman Sachs related humor : Greenspan humor : C Humor : Scripting Humor : Real Programmers Humor : Web Humor : GPL-related Humor : OFM Humor : Politically Incorrect Humor : IDS Humor : "Linux Sucks" Humor : Russian Musical Humor : Best Russian Programmer Humor : Microsoft plans to buy Catholic Church : Richard Stallman Related Humor : Admin Humor : Perl-related Humor : Linus Torvalds Related humor : PseudoScience Related Humor : Networking Humor : Shell Humor : Financial Humor Bulletin, 2011 : Financial Humor Bulletin, 2012 : Financial Humor Bulletin, 2013 : Java Humor : Software Engineering Humor : Sun Solaris Related Humor : Education Humor : IBM Humor : Assembler-related Humor : VIM Humor : Computer Viruses Humor : Bright tomorrow is rescheduled to a day after tomorrow : Classic Computer Humor
The Last but not Least Technology is dominated by two types of people: those who understand what they do not manage and those who manage what they do not understand ~Archibald Putt. Ph.D
Copyright © 1996-2018 by Dr. Nikolai Bezroukov. www.softpanorama.org was initially created as a service to the (now defunct) UN Sustainable Development Networking Programme (SDNP) in the author free time and without any remuneration. This document is an industrial compilation designed and created exclusively for educational use and is distributed under the Softpanorama Content License. Original materials copyright belong to respective owners. Quotes are made for educational purposes only in compliance with the fair use doctrine.
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Last modified: March 22, 2019