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$//' # DOS to Unix sed 's/$/^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 Unix sed $'s/$/\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.
unix2dos, or perhaps
utod) and use them.
If you need to process entire directories and subdirectories, you can use
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.