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 Note: The following information is provided in part by the Extreme Science and Engineering Discovery Environment (XSEDE), a National Science Foundation (NSF) project that provides researchers with advanced digital resources and services that facilitate scientific discovery. For more, see the XSEDE web site.

The format of Windows and Unix text files differs.  In Windows, lines end with both the line feed and carriage return ASCII characters, but Unix uses only a line feed.

There are several utility software to convert text files from UNIX or Linux to DOS operating systems and vice-versa; however, it always helps to know the manual conversion. In shell programming languages like UNIX or Linux the text files conclude with a new line operator"\n" also known as the line feed and its ASCII code is 0A. A DOS Text file concludes a line by the carriage return or the entry key "\r": its ASCII code is 0D. The lines in the DOS end with CRLF or with "\r\n". To convert  DOS text into UNIX or Linux erase the "\r"; you can also use ASCII codes if you are using GNU-sed version.

As a consequence, some Windows applications will not show the line breaks in Unix-format files. Likewise, Unix programs may display the carriage returns in Windows text files with Ctrl-m (^M) characters at the end of each line.


  1. Sometimes when you edit files in Windows and Unix you get a file that have fragments in "Unix style" and fragments in Windows style. dos2unix does not convert such files. Sometime there are even fragments that have only ^M at the end. See How do I convert between Unix an

    In this case you can use multiple Perl one liners along the following lines

    perl -pi -e 's/\r\n/\n/g' input.file
    perl -pi -e 's/\r/\n/g' input.file
  2. To see what problems you have you can use hexdump or Midnight Commander on Unix FAR on Windows. They will show what characters are used in particular file

For simple conversion you can use FTP, screen capture, unix2dos and dos2unix, tr, awk, Perl, and vi to do the conversion. You can also use CYGWIN.


When using an FTP program to move a text file between Unix and Windows, be sure the file is transferred in ASCII format, so the document is transformed into a text format appropriate for the host. Some FTP programs, especially graphical applications (e.g., Hummingbird FTP), do this automatically. If you are using command line FTP, before you begin the transfer, enter:


Note: You need to use a client that supports secure FTP to transfer files to and from Indiana University's central systems. For more, see At IU, what SSH/SFTP clients are supported and where can I get them?

dos2unix and unix2dos

The utilities dos2unix and unix2dos are available for converting files from the Unix command line.

To convert a Windows file to a Unix file, enter:

  dos2unix winfile.txt unixfile.txt

To convert a Unix file to Windows, enter:

  unix2dos unixfile.txt winfile.txt


You can use tr to remove all carriage returns and Ctrl-z (^Z) characters from a Windows file:

  tr -d '\15\32' < winfile.txt > unixfile.txt

However, you cannot use tr to convert a document from Unix format to Windows.


To use awk to convert a Windows file to Unix, enter:

  awk '{ sub("\r$", ""); print }' winfile.txt > unixfile.txt

To convert a Unix file to Windows, enter:

  awk 'sub("$", "\r")' unixfile.txt > winfile.txt

Older versions of awk do not include the sub function. In such cases, use the same command, but replace awk with gawk or nawk.


To convert a Windows text file to a Unix text file using Perl, enter:

  perl -p -e 's/\r$//' < winfile.txt > unixfile.txt

To convert from a Unix text file to a Windows text file, enter:

  perl -p -e 's/\n/\r\n/' < unixfile.txt > winfile.txt

You must use single quotation marks in either command line. This prevents your shell from trying to evaluate anything inside.


In vi, you can remove carriage return ( ^M ) characters with the following command:


Note: To input the ^M character, press Ctrl-v, and then press Enter or return.

In vim, use :set ff=unix to convert to Unix; use :set ff=dos to convert to Windows.

This document was developed with support from National Science Foundation (NSF) grant OCI-1053575. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.
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Ubuntu Genius's Blog

October 26, 2010 | Ubuntu Genius

Most people don't realise that when they hit the Enter key to create a new paragraph in a text file, something very different is going on behind the scenes in the three major operating systems: Windows, Macintosh and Linux. The "end-of-line delimiter" (often expressed as "End-Of-Line", "End of Line", or just "EOL") – which some of you know as the "line break" or "newline" – is a special character used to designate the end of a line within a text file.

UNIX-based operating systems (like all Linux distros and BSD derivatives) use the line feed character (\n or <LF>), "classic" Mac OS uses a carriage return (\r or <CR>), while DOS/Windows uses a carriage return followed by a line feed (\r\n or <CR><LF>). Now that Mac OS X is based on FreeBSD's file system, it follows the UNIX convention.

Now, the reason most people don't know about all this is because nobody really should have to. But while users of Linux distros and Mac OS can open Windows text files in basically any available editor and not even know the difference, the same can't be said for Windows users opening files created in one of the other operating systems.

If you type up a simple text file in Ubuntu and save it in the default "Unix/Linux" format, in Windows it will appear as one continuous paragraph, with black squares where the line breaks (or new paragraphs) should be. While you can open the file in a more advanced text editor (or proper word processor) to view it as it should look, others you've sent it to are just likely to double-click it and let it open in Notepad (which can only handle MS-DOS EOL).

Occasionally, the reverse is the issue, but you can convert Windows text files to UNIX easily with Gedit, as well as convert them via the terminal, so hopefully the following guide will be of use.

For more detailed info on End-Of-Line, go to the Wikipedia page.

Or if you're wanting to do the reverse, check out how to convert to Windows format via the terminal and with Save As… in Gedit.

Converting Windows EOL to Linux via the Terminal

If you find the text editor you're using to display Windows files in Ubuntu shows ^M instead of a line break (not very likely with even the most lightweight text editors, but something you'll probably come across if you display the text in a terminal), don't worry – just convert them to Unix/Linux format.

While you can actually open them in Gedit and use Save As… to save over them (or to create copies) in the correct format, for more than a couple of files this would be the long, complicated solution.

By far the quickest and easiest approach is to convert the offending files via the command-line. This way, you could batch-convert hundreds of such files at once, not have to do them individually.
There are actually quite a few ways to do this, but we'll look at a couple of tiny packages you can install, and the related commands to use.

The first – the tofrodos package – is undoubtedly the most widely-used, so we'll look at that in detail – especially since many of the guides out there are outdated, since the commands it contains have been renamed.

The second is a little package called flip, and since it's tiny and won't cause any issues, it's worth installing as a backup (just in case. I found it useful after trying to get tofrodos going on a new system, before I found out the commands were changed).

There is no actual command tofrodos, as it is just the package that contains the commands todos and fromdos. Currently, the vast majority of online guides will list the commands as unix2dos and dos2unix, but as the developer states:

With this release the symlinks "unix2dos" and "dos2unix" are dropped from the package. This will allow the introduction of the original dos2unix package, which also supports conversion to MacOS style files.

So now you can choose to use either todos (to convert to Windows) and fromdos (to convert to Linux), or just fromdos with options (fromdos -u to convert to DOS, and fromdos -d to convert to UNIX, though obviously the -d option really isn't needed, as it is the default behaviour for the fromdos command).

We'll use fromdos, as it is easier to remember, and show how to alter a single file, or all text files in a given folder. When you're ready to proceed, open a terminal in the folder containing the text file(s) and use one of the following commands (note that for the purpose of illustration, the .txt suffix is used, but you can specify any other extension for your text files).

To Convert to UNIX/Linux via Terminal:

Single file (remember to replace filename.txt with the actual name of the file)

fromdos filename.txt

All text files in a folder (if the extension differs to .txt, simply replace it in the command)

fromdos *.txt

Similarly, flip is easy to use:

flip -u filename.txt (or flip -u *.txt for multiple files)

HowTo UNIX - Linux Convert DOS Newlines CR-LF to Unix-Linux Format

Task: Convert Dos TO Unix Using tr Command

Type the following command:

tr -d '\r' < input.file > output.file

Task: Convert Dos TO Unix Using Perl One Liner

Type the following command:

perl -pi -e 's/\r\n/\n/g' input.file

Task: Convert UNIX to DOS format using sed command

Type the following command:

$ sed 's/$'"/`echo \\\r`/" input.txt > output.txt 
Note: sed version may not work under different UNIX/Linux variant,refer your 
	local sed man page for more info.

Task: Convert DOS newlines (CR/LF) to Unix format using sed command

If you are using BASH shell type the following command (press Ctrl-V then Ctrl-M to get pattern or special symbol)

$ sed 's/^M$//' input.txt > output.txt
Note: sed version may not work under different UNIX/Linux variant, refer your local sed man page for more info.

Converting DOS-UNIX and vice-versa

The text files under Unix end their line with the symbol "\n" (called Line Feed and noted LF, ASCII code = 0A).

Text files under DOS by a "line", end their line with the symbol "\r"(called Carriage Return and noted CR, ASCII 0D).
Thus, every line in a DOS file ends with a CRLF sequence, or \r\n.

Conversion from DOS to UNIX

Simply delete the "\r" (carriage return) at the end of the line.
The "\ r" is symbolically represented by "^M", which is obtained by the following sequence of keys "CTRL-V" + "CTRL-M".

sed 's/^M$//' file


With the GNU-sed(gsed 3.02.80) version, we can use the ASCII notation:

sed 's/\x0D$//' file

Conversion from UNIX to DOS

Just do the opposite of the previous command, namely (the "^M" being entered in the same way (CTRL-V + CTRL-M)):
sed 's/$/^M/' file

With the GNU-sed(gsed 3.02.80) version, we can use the symbolic notation "\r":

sed 's/$/\r/' file

Recommended Links

HowTo UNIX - Linux Convert DOS Newlines CR-LF to Unix-Linux Format

Converting DOS-UNIX and vice-versa

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