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

by Vivek Gite · 6 comments

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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{ 6 comments… read them below or add one }

1 bruce wolford 01.04.07 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.
2 nigel 02.02.07 at 1:42 pm: I had tried the suggestion from Wikipedia and that did not work. This solution worked perfectly first time. THANK YOU.
3 John Cairns 09.05.07 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.
4 Calvin Smith 12.12.07 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)
5 David Schiavone 08.13.09 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 ;).
6 Dzmitry Lazerka 11.13.09 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.