How to convert DOS/Windows newline (CRLF) to Unix newline (LF) in a Bash script

You can use tr to convert from DOS to Unix; however, you can only do this safely if CR appears in your file only as the first byte of a CRLF byte pair. This is usually the case. You then use:

tr -d '\015' <DOS-file >UNIX-file

Note that the name DOS-file is different from the name UNIX-file; if you try to use the same name twice, you will end up with no data in the file.

You can't do it the other way round (with standard 'tr').

If you know how to enter carriage return into a script (control-V, control-M to enter control-M), then:

sed 's/^M$//'     # DOS to Unixsed 's/$/^M/'     # Unix to DOS

where the '^M' is the control-M character. You can also use the bash ANSI-C Quoting mechanism to specify the carriage return:

sed $'s/\r$//'     # DOS to Unixsed $'s/$/\r/'     # Unix to DOS

However, if you're going to have to do this very often (more than once, roughly speaking), it is far more sensible to install the conversion programs (e.g. dos2unix and unix2dos, or perhaps dtou and utod) and use them.

If you need to process entire directories and subdirectories, you can use zip:

zip -r -ll zipfile.zip somedir/unzip zipfile.zip

This will create a zip archive with line endings changed from CRLF to CR. unzip will then put the converted files back in place (and ask you file by file - you can answer: Yes-to-all). Credits to @vmsnomad for pointing this out.

Use:

tr -d "\r" < file

Take a look here for examples using sed:

# In a Unix environment: convert DOS newlines (CR/LF) to Unix format.sed 's/.$//'               # Assumes that all lines end with CR/LFsed 's/^M$//'              # In Bash/tcsh, press Ctrl-V then Ctrl-Msed 's/\x0D$//'            # Works on ssed, gsed 3.02.80 or higher# In a Unix environment: convert Unix newlines (LF) to DOS format.sed "s/$/`echo -e \\\r`/"            # Command line under kshsed 's/$'"/`echo \\\r`/"             # Command line under bashsed "s/$/`echo \\\r`/"               # Command line under zshsed 's/$/\r/'                        # gsed 3.02.80 or higher

Use sed -i for in-place conversion, e.g., sed -i 's/..../' file.

You can use Vim programmatically with the option -c {command}:

DOS to Unix:

vim file.txt -c "set ff=unix" -c ":wq"

Unix to DOS:

vim file.txt -c "set ff=dos" -c ":wq"

"set ff=unix/dos" means change fileformat (ff) of the file to Unix/DOS end of line format.

":wq" means write the file to disk and quit the editor (allowing to use the command in a loop).