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The mount command serves to attach the file system found on some device to the big file tree.
It takes two parameters: first is device and the second mount point. Essentially the same semantec as cp command.
Conversely, the umount command will detach it again. When mounting USB drive,
is your friend. It helps to find the right device name to mount
In Suse Linux the available devices are also visible in YAST/system/hardware.
When you mount a partition, this the root directory on which you mount particular partition effectively substitutes the name of the directory on which it is mounted, but all attributes of the partition comes from the root direction on the mounted partition.
So, for example, when you see /tmp directory on which a partition is mounted you see the root directory of this partition under the name of /tmp with all its attributes, not the /tmp directory that exists in root partition with its attaributes. That means that by the mere fact of mounting partition on the directory, the permissions and ownership of the directory can change.
That's usually a big surprise for junior sysadmins. Typically such shock is experienced when you extent /tmp partition by creating a new partition and changing the mount point in /etc/fstab. Unless you check new /tmp partition attributes, as a result after the reboot /tmp typically is not world writable and does not have a sticky attribute set ;-)
In other words, if you created a new partition (say on a new disk) and mount it, say, on /tmp (for example to enlarge partition) it is this new partition root directory attributes that are visible, not the attributes of the /tmp directory that exists in root directory whatever they are. That's why there is no sticky bit such a newly mounted /tmp partition and that's why typically it is not world-writable (aka "public") as /tmp should be (and BTW if you work as root this fact is not immediately visible as for root it is writable; this is another argument in favor of using sudo by sysadmins ;-).
|When a partition is mounted then the root directory of the partition substitutes (overlay) the directory on which it is mounted.|
That is connected with the implemented in Unix concept of mounting. When a partition is mounted then the root directory of the partition substitutes (overlay) the directory on which it is mounted.
mount [-t type] device dir tells the kernel to attach the file system found on device (which is of type type) at the directory dir. The previous contents (if any) and owner and mode of dir become invisible, and as long as this file system remains mounted, the pathname dir refers to the root of the file system on device.
And by default permission for this newly-created "hidden" root directory are defined by umask. It is something like 755, never 1777.
Similarly if you unmount old /tmp and mount it of, say, /srv, this directory magically will get permission 1777 despite the fact that before that the permission on the /srv directory were 755.
Sometime dir to errors in RAID controller or disks the partition isswitch to read write. If error is episodic you can switch it back for some period of time, befire it bane read only afain.
To remount file system in read-write mode use below command –
# mount -o remount,rw /home
To see the results see
# mount -v | grep home
Note: It is recommended to fsck file system before re mounting it.
Sometimes if there are errors in /etc/fstab the system can't boot properly and come in rescue mode. In this mode the only drive (root) is mounted as read-only. To remount the root volume as writable you can use the command:
mount -o remount,rw /
If you make changes to /etc/fstab you can remount all filesystems listed in /etc/fstab/.
mount -o remount -a
The -o remount may not be able to change mount parameters (all ext3-specific parameters, except sb, are changeable with a remount, for example, but you can't change gid or umask for the fatfs).
Linux has a unique option in mount command which permits to move a mounted partition to new mounting point.
mount --move olddir newdir
Some files such as ISO files, DD images, and archives (for example zip archives) etc can be viewed as pseudopartitions.
The most typical use of this feature is mounting ISO images.
mount -o loop /tmp/test.img /mnt/image
See Linux Loopback filesystem for details
to unmount partition you can use umount command. For example
But it is not always succeed. One reason that the partition can't be unmounted is that it is used by some
application. Thre revelnet command to detect why are
lsof and fuser
Fist you need to understand the situation. The first step is to find out what processes have activities on the device/partition. This can be done using lsof command. for example:
# lsof | grep '/dev/sda1'
Now you know what processes to stop. As soon those process are killed (you can use fuser -km mount_point for that), the device will no longer be busy and you can unmount it with the following command
You can also try to find which user is preventing the partition from unmount using that command fuser -u mount_point
After that you can kill all processes at once using the command fuser -km file_or_directory
With kernel version 2.6 you try to use option -l to initiated so called lazy unmount. System will unmount the filesystem as soon as it is not busy anymore. For example:
# umount -l /opt
for NFS special option -f exist, which forces unmount of unreachable NFS filesystem.
# umount -f /opt/sge
mount -o remount,rw /If you make changes to /etc/fstab you can remount all filesystems listed in /etc/fstab/.
mount -o remount -a
mount -f iso9660 /dev/dvd /media
mount -o loop /tmp/test.img /mnt/image
mount --move olddir newdir
mount --bind olddir newdir
remount the filesystem mounted on olddir to newdir. This call attaches only (part of) a single filesystem, not possible submounts. The entire file hierarchy including submounts is attached a second place using. After this call the same contents is accessible in two places. One can also remount a single file (on a single file).
mount --rbind olddir newdir
Note: the filesystem mount options will remain the same as those on the original
mount point, and cannot be changed by passing the -o option along with --bind/--rbind.
Most devices are indicated by a file name (of a block special device), like /dev/sda1, but there are other possibilities. For example, in the case of an NFS mount, device may look like knuth.cwi.nl:/dir. It is possible to indicate a block special device using its volume label or UUID (see the -L and -U options).
The file /etc/fstab (see fstab(5)), may contain lines describing what devices are usually mounted where, using which options. This file is used in three ways:
When mounting a file system mentioned in fstab, it suffices to give only the device, or only the mount point.
Normally, only the superuser can mount file systems. However, when fstab contains the user option on a line, anybody can mount the corresponding system. Thus, given a line
/dev/cdrom /media/dvd iso9660 ro,user,noauto,unhideany user can mount the iso9660 file system found on his CDROM using the command
mount /media/dvdFor more details, see fstab(5).
Only the user that mounted a filesystem can unmount it again. If any user should be able to unmount, then use users instead of user in the fstab line.
The owner option is similar to the user option, with the restriction that the user must be the owner of the special file. This may be useful e.g. for /dev/fd if a login script makes the console user owner of this device. The group option is similar, with the restriction that the user must be member of the group of the special file.
The programs mount and umount maintain a list of currently mounted file systems in the file /etc/mtab. If no arguments are given to mount, this list is printed.
When the proc filesystem is mounted (say at /proc), the files /etc/mtab and /proc/mounts have very similar contents. The former has somewhat more information, such as the mount options used, but is not necessarily up-to-date (cf. the -n option below). It is possible to replace /etc/mtab by a symbolic link to /proc/mounts, and especially when you have very large numbers of mounts things will be much faster with that symlink, but some information is lost that way, and in particular working with the loop device will be less convenient, and using the "user" option will fail.
Since Linux 2.6.15 it is possible to mark a mount and its submounts as shared, private, slave or unbindable.
Detailed semantics is documented in Documentation/sharedsubtree.txt file in the kernel source tree.
mount --make-shared mountpoint mount --make-slave mountpoint mount --make-private mountpoint mount --make-unbindable mountpoint
The following commands allows one to recursively change the type of all the mounts under a given mountpoint.
mount --make-rshared mountpoint mount --make-rslave mountpoint mount --make-rprivate mountpoint mount --make-runbindable mountpoint
The proc file system is not associated with a special device, and when mounting it, an arbitrary keyword, such as proc can be used instead of a device specification. (The customary choice none is less fortunate: the error message 'none busy' from umount can be confusing.)
Jan 14, 2018 | kerneltalks.com/n /n/n
Most of the time on newly created file systems of NFS filesystems we see error/n like below :/n/n
/n/n 1 2 3 4/n/n root @ kerneltalks # touch file1 touch : cannot touch ' file1 ' : Read - only file/n system/n
This is because file system is mounted as read only. In such scenario you have to mount it/n in read-write mode. Before that we will see how to check if file system is mounted in read only/n mode and then we will get to how to re mount it as a read write filesystem./n
/n How to check if file system is read only/n/n
To confirm file system is mounted in read only mode use below command –/n/n
/n/n 1 2 3 4/n/n # cat /proc/mounts | grep datastore / dev / xvdf / datastore ext3 ro , seclabel ,/n relatime , data = ordered 0 0/n
Grep your mount point in/n/n
cat /proc/mountsand observer third column which shows/n all options which are used in mounted file system. Here
rodenotes file system is/n mounted read-only.
You can also get these details using/n/n
/n/n 1 2 3 4/n/n root @ kerneltalks # mount -v |grep datastore / dev / xvdf on / datastore type ext3 (/n ro , relatime , seclabel , data = ordered )/n
In this output. file system options are listed in braces at last column./n
/n Re-mount file system in read-write mode/n/n
To remount file system in read-write mode use below command –/n/n
/n/n 1 2 3 4 5 6/n/n root @ kerneltalks # mount -o remount,rw /datastore root @ kerneltalks # mount -v |grep/n datastore / dev / xvdf on / datastore type ext3 ( rw , relatime , seclabel , data = ordered/n )/n
Observe after re-mounting option/n/n
rw. Now, file/n system is mounted as read write and now you can write files in it./n/n/n
Note : It is recommended to/n
fsckfile system before re mounting it.
You can check file system by running/n/n
fsckon its volume.
/n/n 1 2 3 4 5 6 7 8 9 10/n/n root @ kerneltalks # df -h /datastore Filesystem Size Used Avail Use % Mounted on / dev/n / xvda2 10G 881M 9.2G 9 % / root @ kerneltalks # fsck /dev/xvdf fsck from util - linux/n 2.23.2 e2fsck 1.42.9 ( 28 - Dec - 2013 ) / dev / xvdf : clean , 12 / 655360 files , 79696 //n 2621440 blocks/n
Sometimes there are some corrections needs to be made on file system which needs reboot to/n make sure there are no processes are accessing file system./n /n /n
January 27, 2006 | www.cyberciti.biz/n/n/n
... ... .../n/n
Linux / UNIX will not allow you to unmount a device that is busy. There are many reasons for this /n (such as program accessing partition or open file) , but the most important one is to prevent /n the data loss. Try the following command to find out what processes have activities on the /n device/partition. If your device name is /dev/sdb1, enter the following command as root user:/n/n# lsof | grep '/dev/sda1'/n Output:vi 4453 vivek 3u BLK 8,1 8167 /dev/sda1/n/n
Above output tells that user vivek has a vi process running that is using /dev/sda1. All you have /n to do is stop vi process and run umount again. As soon as that program terminates its task, the device /n will no longer be busy and you can unmount it with the following command:/n/n# umount /dev/sda1/n/n How do I list the users on the file-system /nas01/?
Type the following command:/n/n# fuser -u /nas01//n Sample outputs:
/n # fuser -u /var/www//var/www: 3781rc(root) 3782rc(nginx) 3783rc(nginx) 3784rc(nginx) 3785rc(nginx) 3786rc(nginx) 3787rc(nginx) 3788rc(nginx) 3789rc(nginx) 3790rc(nginx) 3791rc(nginx) 3792rc(nginx) 3793rc(nginx) 3794rc(nginx) 3795rc(nginx) 3796rc(nginx) 3797rc(nginx) 3798rc(nginx) 3800rc(nginx) 3801rc(nginx) 3802rc(nginx) 3803rc(nginx) 3804rc(nginx) 3805rc(nginx) 3807rc(nginx) 3808rc(nginx) 3809rc(nginx) 3810rc(nginx) 3811rc(nginx) 3812rc(nginx) 3813rc(nginx) 3815rc(nginx) 3816rc(nginx) 3817rc(nginx)/n/n
The following discussion allows you to unmount device and partition forcefully using mount or fuser /n Linux commands./n Linux fuser command to forcefully unmount a disk partition
Suppose you have /dev/sda1 mounted /n on /mnt directory then you can use fuser command as follows:/n WARNING! These examples may result into data loss if not executed properly (see /n "Understanding /n device error busy error" for more information).
Type the command to unmount /mnt forcefully:/n/n# fuser -km /mnt/n Where,
- -k : Kill processes accessing the file./n/n
- -m : Name specifies a file on a mounted file system or a block device that is mounted. In /n above example you are using /mnt/n
Linux umount command to unmount a disk partition./n/n
You can also try the umount command with –l option on a Linux based system:/n/n# umount -l /mnt/n Where,
- -l : Also known as Lazy unmount. Detach the filesystem from the filesystem hierarchy now, /n and cleanup all references to the filesystem as soon as it is not busy anymore. This option works /n with kernel version 2.4.11+ and above only./n
If you would like to unmount a NFS mount point then try following command:/n/n# umount -f /mnt/n Where,
- -f: Force unmount in case of an unreachable NFS system/n
Please note that using these commands or options can cause data loss for open files; programs /n which access files after the file system has been unmounted will get an error./n/n
January 27, 2006 | www.cyberciti.biz
... ... ...
Linux / UNIX will not allow you to unmount a device that is busy. There are many reasons for this (such as program accessing partition or open file) , but the most important one is to prevent the data loss. Try the following command to find out what processes have activities on the device/partition. If your device name is /dev/sdb1, enter the following command as root user:# lsof | grep '/dev/sda1'Output:vi 4453 vivek 3u BLK 8,1 8167 /dev/sda1
Above output tells that user vivek has a vi process running that is using /dev/sda1. All you have to do is stop vi process and run umount again. As soon as that program terminates its task, the device will no longer be busy and you can unmount it with the following command:
# umount /dev/sda1How do I list the users on the file-system /nas01/?
Type the following command:
# fuser -u /nas01/
# fuser -u /var/www/
Sample outputs:/var/www: 3781rc(root) 3782rc(nginx) 3783rc(nginx) 3784rc(nginx) 3785rc(nginx) 3786rc(nginx) 3787rc(nginx) 3788rc(nginx) 3789rc(nginx) 3790rc(nginx) 3791rc(nginx) 3792rc(nginx) 3793rc(nginx) 3794rc(nginx) 3795rc(nginx) 3796rc(nginx) 3797rc(nginx) 3798rc(nginx) 3800rc(nginx) 3801rc(nginx) 3802rc(nginx) 3803rc(nginx) 3804rc(nginx) 3805rc(nginx) 3807rc(nginx) 3808rc(nginx) 3809rc(nginx) 3810rc(nginx) 3811rc(nginx) 3812rc(nginx) 3813rc(nginx) 3815rc(nginx) 3816rc(nginx) 3817rc(nginx)
The following discussion allows you to unmout device and partition forcefully using mount or fuser Linux commands.Linux fuser command to forcefully unmount a disk partition
Suppose you have /dev/sda1 mounted on /mnt directory then you can use fuser command as follows:WARNING! These examples may result into data loss if not executed properly (see "Understanding device error busy error" for more information).
Type the command to unmount /mnt forcefully:# fuser -km /mntWhere,
- -k : Kill processes accessing the file.
- -m : Name specifies a file on a mounted file system or a block device that is mounted. In above example you are using /mnt
Linux umount command to unmount a disk partition.
You can also try the umount command with –l option on a Linux based system:# umount -l /mntWhere,
- -l : Also known as Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. This option works with kernel version 2.4.11+ and above only.
If you would like to unmount a NFS mount point then try following command:# umount -f /mntWhere,
- -f: Force unmount in case of an unreachable NFS system
Please note that using these commands or options can cause data loss for open files; programs which access files after the file system has been unmounted will get an error.
(note: I started this thread at http://ubuntuforums.org/showthread.php?t=412717), but it hasn't been getting much response there. I'm hoping it will fit in better here. http://www.suseforums.net/index.php?showtopic=34332 is also a related post in the SUSE forums.)
I've been reading various tutorials on fstab and mounting, but I still don't really understand. There are varying ways to achieve the same end results -- and nowhere among the most popular general fstab guides/tutorials are there many examples of typical partition types and their common mount strategies.
So, what I would like to do is to make a different kind of guide. I'd like to compile a list of typical partition types and common fstab entries for them and give concise explanations for why each element is chosen. I will edit this as feedback comes in and it will essentially publish itself here.
If this kind of guide already exists, it is well hidden. So, please, help me form this into something useful.
If this ever gets done -- done well, please feel free to post this somewhere else or to translate the commentary. Please do link back to this as the source and help me keep this thread updated. Email me (conquest [at] spamcop [dot] net) if the thread gets old and you'd like to see an alteration of the top post. Maybe making a wiki would be good for this too. I'll do that if it seems appropriate.
Situation 1: Windows partitions (NT, 2000, XP, 2003, Vista)Code:
1A/dev/xxxx /media/mountpoint ntfs user,ro,auto 0 0(user allows anyone to mount, ro makes it read-only since ntfs is a MS-protected format, auto mounts it at boot automatically)
1B Code:/dev/xxxx /media/mountpoint ntfs nls=utf8,umask=0222 0 0(nls=utf8 includes unicode for non-English users, umask=0222 (-r-xr-xr-x) does what?)
1C Code:/dev/xxxx /media/mountpoint ntfs defaults,nls=utf8,umask=007,gid=46 0 1(nls=utf8 includes unicode for non-English users, umask=007 ??? Makes for 659 permissions?, gid=46 ??? )
Situation 2: ntfs data partitions (generally from Windows):Code:
(same as above???)Situation 3: fat-32 data partitions (ideal shared partition between linux, windows, and apple's mac os):
Code:/dev/xxxx /media/mountpoint vfat iocharset=utf8,umask=000 0 0(iocharset=utf8 includes unicode for non-English users, umask=000 allows most liberal file permissions)
Situation 4: ext3 data partitions (partitions shared between different linuxes, mac osx, and even Windows (using "Ext2 Installable File System for Windows", for example)):Code:
I don't know. I can find no examples of this on the fstab tutorials. Maybe /dev/xxxx /media/mountpoint ext3 defaults 0 2Situation 5: other linuxes themselves, their root partition:
Code:??? again, maybe /dev/xxxx /media/mountpoint ext3 defaults 0 2The format of fstab is also changing, from something like this:
Code:/dev/sda2 /media/sda2 ntfs defaults,nls=utf8,umask=007,gid=46 0 1to something like this:
Code:# /dev/sda2 UUID=9068AF8E68AF7220 /media/sda2 ntfs defaults,nls=utf8,umask=007,gid=46 0 1However, I cannot find any authoritative links on this:
http://ubuntuforums.org/showthread.php?t=405630 (My device are now "sda" than "hda")
http://www.linuxquestions.org/questi...d.php?t=544734 (ide drives show up as special device)
Can anyone point out where this transition is explained, please? An announcement somewhere?
key phrases: typical mount options, example fstab's, example fstab,
http://www.zzee.com/solutions/linux-permissions.shtml (linux permissions)
http://linux.about.com/cs/linux101/g/gid.htm (About.com's short note on GID)
http://www.die.net/doc/linux/man/man1/uuid.1.html (man page for uuid)
http://www.die.net/doc/linux/man/man8/mount.8.html (man page for mount)
http://www.tuxfiles.org/linuxhelp/fstab.html (top guide according to google -- no fixed-drive examples are given, though)
http://www.psychocats.net/ubuntu/mountwindows has several example fstab entries, but it has little to no explanation of those mount options.
http://www.linuxquestions.org/linux/..._and_explained (another fstab tutorial)
The full set of options used by an invocation of mount is determined by first extracting the options for the file system from the fstab table, then applying any options specified by the -o argument, and finally applying a -r or -w option, when present.
Options available for the mount command:
For most types all the mount program has to do is issue a simple mount(2) system call, and no detailed knowledge of the filesystem type is required. For a few types however (like nfs, nfs4, cifs, smbfs, ncpfs) ad hoc code is necessary. The nfs ad hoc code is built in, but cifs, smbfs, and ncpfs have a separate mount program. In order to make it possible to treat all types in a uniform way, mount will execute the program /sbin/mount.TYPE (if that exists) when called with type TYPE. Since various versions of the smbmount program have different calling conventions, /sbin/mount.smbfs may have to be a shell script that sets up the desired call.
If no -t option is given, or if the auto type is specified, mount will try to guess the desired type. If mount was compiled with the blkid library, the guessing is done by this library. Otherwise, mount guesses itself by probing the superblock; if that does not turn up anything that looks familiar, mount will try to read the file /etc/filesystems, or, if that does not exist, /proc/filesystems. All of the filesystem types listed there will be tried, except for those that are labeled "nodev" (e.g., devpts, proc, nfs, and nfs4). If /etc/filesystems ends in a line with a single * only, mount will read /proc/filesystems afterwards.
The auto type may be useful for user-mounted floppies. Creating a file /etc/filesystems can be useful to change the probe order (e.g., to try vfat before msdos or ext3 before ext2) or if you use a kernel module autoloader. Warning: the probing uses a heuristic (the presence of appropriate 'magic'), and could recognize the wrong filesystem type, possibly with catastrophic consequences. If your data is valuable, don't ask mount to guess.
More than one type may be specified in a comma separated list. The list of file system types can be prefixed with no to specify the file system types on which no action should be taken. (This can be meaningful with the -a option.)
For example, the command:
It is different from -t in that each option is matched exactly; a leading no at the beginning of one option does not negate the rest.
The -t and -O options are cumulative in effect; that is, the command
mount -a -t ext2 -O _netdevmounts all ext2 filesystems with the _netdev option, not all filesystems that are either ext2 or have the _netdev option specified.
- All I/O to the file system should be done asynchronously.
- Update inode access time for each access. This is the default.
- Can be mounted with the -a option.
- Use default options: rw, suid, dev, exec, auto, nouser, and async.
- Interpret character or block special devices on the file system.
- Permit execution of binaries.
- Allow an ordinary (i.e., non-root) user to mount the file system if one of his groups matches the group of the device. This option implies the options nosuid and nodev (unless overridden by subsequent options, as in the option line group,dev,suid).
- Allow mandatory locks on this filesystem. See fcntl(2).
- The filesystem resides on a device that requires network access (used to prevent the system from attempting to mount these filesystems until the network has been enabled on the system).
- Do not update inode access times on this file system (e.g, for faster access on the news spool to speed up news servers).
- Do not update directory inode access times on this filesystem.
- Can only be mounted explicitly (i.e., the -a option will not cause the file system to be mounted).
- Do not interpret character or block special devices on the file system.
- Do not allow direct execution of any binaries on the mounted file system. (Until recently it was possible to run binaries anyway using a command like /lib/ld*.so /mnt/binary. This trick fails since Linux 2.4.25 / 2.6.0.)
- Do not allow mandatory locks on this filesystem.
- Do not allow set-user-identifier or set-group-identifier bits to take effect. (This seems safe, but is in fact rather unsafe if you have suidperl(1) installed.)
- Forbid an ordinary (i.e., non-root) user to mount the file system. This is the default.
- Allow an ordinary (i.e., non-root) user to mount the file system if he is the owner of the device. This option implies the options nosuid and nodev (unless overridden by subsequent options, as in the option line owner,dev,suid).
- Attempt to remount an already-mounted file system. This is commonly used to change the mount flags for a file system, especially to make a readonly file system writeable. It does not change device or mount point.
- Mount the file system read-only.
- Mount the file system read-write.
- Allow set-user-identifier or set-group-identifier bits to take effect.
- All I/O to the file system should be done synchronously. In case of media with limited number of write cycles (e.g. some flash drives) "sync" may cause life-cycle shortening.
- All directory updates within the file system should be done synchronously. This affects the following system calls: creat, link, unlink, symlink, mkdir, rmdir, mknod and rename.
- Allow an ordinary user to mount the file system. The name of the mounting user is written to mtab so that he can unmount the file system again. This option implies the options noexec, nosuid, and nodev (unless overridden by subsequent options, as in the option line user,exec,dev,suid).
- Allow every user to mount and unmount the file system. This option implies the options noexec, nosuid, and nodev (unless overridden by subsequent options, as in the option line users,exec,dev,suid).
- context=context, fscontext=context and defcontext=context
- The context= option is useful when mounting filesystems that do not support extended attributes, such as a floppy or hard disk formatted with VFAT, or systems that are not normally running under SELinux, such as an ext3 formatted disk from a non-SELinux workstation. You can also use context= on filesystems you do not trust, such as a floppy. It also helps in compatibility with xattr-supporting filesystems on earlier 2.4.<x> kernel versions. Even where xattrs are supported, you can save time not having to label every file by assigning the entire disk one security context.
A commonly used option for removable media is context=system_u:object_r:removable_t.
Two other options are fscontext= and defcontext=, both of which are mutually exclusive of the context option. This means you can use fscontext and defcontext with each other, but neither can be used with context.
The fscontext= option works for all filesystems, regardless of their xattr support. The fscontext option sets the overarching filesystem label to a specific security context. This filesystem label is separate from the individual labels on the files. It represents the entire filesystem for certain kinds of permission checks, such as during mount or file creation. Individual file labels are still obtained from the xattrs on the files themselves. The context option actually sets the aggregate context that fscontext provides, in addition to supplying the same label for individual files.
You can set the default security context for unlabeled files using defcontext= option. This overrides the value set for unlabeled files in the policy and requires a file system that supports xattr labeling.
For more details see selinux(8)
What options are supported depends a bit on the running kernel. More info may be found in the kernel source subdirectory Documentation/filesystems.
% mount /k -o minixdf; df /k; umount /k Filesystem 1024-blocks Used Available Capacity Mounted on /dev/sda6 2630655 86954 2412169 3% /k % mount /k -o bsddf; df /k; umount /k Filesystem 1024-blocks Used Available Capacity Mounted on /dev/sda6 2543714 13 2412169 0% /k(Note that this example shows that one can add command line options to the options given in /etc/fstab.)
Programs that do computed lseeks won't like in-kernel text conversion. Several people have had their data ruined by this translation. Beware!
For file systems mounted in binary mode, a conversion tool (fromdos/todos) is available.
Normal iso9660 filenames appear in a 8.3 format (i.e., DOS-like restrictions on filename length), and in addition all characters are in upper case. Also there is no field for file ownership, protection, number of links, provision for block/character devices, etc.
Rock Ridge is an extension to iso9660 that provides all of these unix like features. Basically there are extensions to each directory record that supply all of the additional information, and when Rock Ridge is in use, the filesystem is indistinguishable from a normal UNIX file system (except that it is read-only, of course).
The following options are the same as for vfat and specifying them only makes sense when using discs encoded using Microsoft's Joliet extensions.
Especially useful options include
Especially useful options include
The default is "lower".
mount /tmp/fdimage /mnt -t msdos -o loop=/dev/loop3,blocksize=1024will set up the loop device /dev/loop3 to correspond to the file /tmp/fdimage, and then mount this device on /mnt.
This type of mount knows about three options, namely loop, offset and encryption, that are really options to losetup(8). (These options can be used in addition to those specific to the filesystem type.)
If no explicit loop device is mentioned (but just an option '-o loop' is given), then mount will try to find some unused loop device and use that. If you are not so unwise as to make /etc/mtab a symbolic link to /proc/mounts then any loop device allocated by mount will be freed by umount. You can also free a loop device by hand, using 'losetup -d', see losetup(8).
Some Linux file systems don't support -o sync and -o dirsync (the ext2, ext3, fat and vfat file systems do support synchronous updates (a la BSD) when mounted with the sync option).
The -o remount may not be able to change mount parameters (all ext2fs-specific parameters, except sb, are changeable with a remount, for example, but you can't change gid or umask for the fatfs).
Mount by label or uuid will work only if your devices have the names listed in /proc/partitions. In particular, it may well fail if the kernel was compiled with devfs but devfs is not mounted.
It is possible that files /etc/mtab and /proc/mounts don't match. The first file is based only on the mount command options, but the content of the second file also depends on the kernel and others settings (e.g. remote NFS server. In particular case the mount command may reports unreliable information about a NFS mount point and the /proc/mounts file usually contains more reliable information.)
Checking files on NFS filesystem referenced by file descriptors (i.e. the fcntl and ioctl families of functions) may lead to inconsistent result due to the lack of consistency check in kernel even if noac is used.
A mount command existed in Version 5 AT&T UNIX.
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