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

by on August 28, 2006 · 18 comments· LAST UPDATED December 31, 2009

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How do I convert DOS newlines CR/LF to Unix/Linux format?

To converts text files between DOS and Unix formats you need to use special utility called dos2unix. DOS text files traditionally have carriage return and line feed pairs as their newline characters while Unix text files have the line feed as their newline character.

UNIX/Linux Commands

You can use the following tools:

  • dos2unix (also known as fromdos) - converts text files from the DOS format to the Unix
    format
  • unix2dos (also known as todos) - converts text files from the Unix format to the DOS format.
  • sed - You can use sed command for same purpose
  • tr command
  • Perl one liner

Task: Convert DOS file to UNIX format

Type the following command to convert file called myfile.txt:
$ dos2unix myfile.txt

However above command will not make a backup of original file myfile.txt. To make a backup of original file. The original file is renamed with the original filename and a .bak extension. Type the following command:
$ dos2unix -b myfile.txt

Task: Convert UNIX file to DOS format

Type the following command to convert file called myfile.txt:
$ unix2dos myfile.txt
$ unix2dos -b myfile.txt

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 if you are using bash shell:
$ 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.

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{ 18 comments… read them below or add one }

1 bruce wolford January 4, 2007 at 2:10 am

Howto: UNIX or Linux convert DOS newlines CR-LF to Unix/Linux format

THANK YOU! to who ever wrote this. I’ve been messing around with this for quite a while. This even works on AIX’s legacy version of sed. My day has been so made by this little nugget.

Reply

2 nigel February 2, 2007 at 1:42 pm

I had tried the suggestion from Wikipedia and that did not work. This solution worked perfectly first time. THANK YOU.

Reply

3 John Cairns September 5, 2007 at 2:44 pm

Your UNIX to DOS sed script is incorrect if what you want is CRLF.

$ echo | sed ‘s/$'”/`echo \\\r`/” | hexdump
0000000 0a0d

ASCII 0/13 is decimal 013, hex 0d, octal 015, bits 00001101: called ^M, CR
Official name: Carriage Return

ASCII 0/10 is decimal 010, hex 0a, octal 012, bits 00001010: called ^J, LF, NL
Official name: Line Feed

For CRLF you want 0d0a. Your producing LFCR here.

Reply

4 Calvin Smith December 12, 2007 at 6:23 am

Dear John,

Actually, the scripts are correct. Hexdump is reversing the byte order (integer format)

Try this for example and as a simplified script:

$ echo TEST | sed ‘s/$/\r/’ | hexdump -C

Then try it without the -C.
You will notice that the 54’s (T) are next to each other. (ETTS)

Reply

5 David Schiavone August 13, 2009 at 10:49 am

Impressive i would say.. I used dos2unix on CentOS 5.3 without any problems and a file of 300,000 got modified in less then 15 secs… compared it to using notepad++ on windows and your computer would freeze up for at least 2 mins for the same file ;).

Reply

6 Dzmitry Lazerka November 13, 2009 at 9:33 am

sed ‘s/$'”/`echo \\\r`/” input.txt > output.txt
leaves one extra CR at the end of the file.
This makes the suggestion broken.

Reply

7 Allan October 5, 2010 at 2:25 pm

The sed … echo \\\r worked fine for us on AIX version 6.1 to convert Unix to DOS. Thanks!

Reply

8 sankar November 10, 2010 at 8:12 am

I have to convert 50 files at one shot to Unix format. Is there a way to do it?

Reply

9 nixCraft November 10, 2010 at 10:47 am

Use bash for loop:

for f in /path/to/src/*
do
  dos2unix "$f"
done

Reply

10 Steen January 29, 2012 at 10:50 pm

Even easier:
$cd dir/with/stuff
$dos2unix *

Reply

11 Sunil March 3, 2011 at 1:27 am

Do we have dos2unix equivalent command on Window OS. Ie. A Window command to convert dos newlines to unix format.

Thanks for your help.

Reply

12 Steen January 29, 2012 at 10:49 pm

Thanks!
I was just about to write a shellscript for this, but then I just googled it because I forgot if it was /n to /r or how :P It works!!!

Side note:
For people with problems about duplicates moved from Windows to Linux on Garry’s Mod servers they should use “dos2unix STEAM*/*.txt” to avoid trying to convert directories. There’s a lot of trouble with user created directories otherwise. The program tries to convert directories – which is a bit annoying.

Reply

13 kevin July 13, 2012 at 3:54 pm

I found the sed unix to dos to not work, it ended up leaving CRs at the end of lines and CRLF at the start of every line….

instead the following correctly left CRLFs at the end of every line (that originally had LFs)

sed “s/$/`echo`/” on Ubuntu BASH

Reply

14 Ayyaz July 27, 2012 at 5:45 pm

I want to know that can a DOS (Linux) support the Microsoft widow XP. if yes then how?

Reply

15 vinil October 28, 2012 at 1:10 pm

how o convert DOS CR/LF files to UNIX files in which lines end in LF?

Reply

16 simhe February 14, 2013 at 8:27 am

Task: Convert Unix TO Dos Using Perl One Liner

perl -pi -e ‘s/\n/\r\n/g’ input.file

Reply

17 Cyrus May 13, 2013 at 1:09 am

For me, `tr -d ‘\r’ output.file` deletes all the carriage returns without replacing them with newlines. `tr ‘\r’ ‘\n’ output.file` works nicely, though

Reply

18 Josiah Yoder July 24, 2013 at 4:20 pm

You might also suggest
sed ‘s/$/\r/’
This works fine on Cygwin sed, though perhaps not for that pesky last line.

Thanks for the suggestions.

Reply

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