Remove carriage return in Unix

Question

What is the simplest way to remove all the carriage returns \\r from a file in Unix?

Answer 1

Removing \r on any UNIX® system:

Most existing solutions in this question are GNU-specific, and wouldn't work on OS X or BSD; the solutions below should work on many more UNIX systems, and in any shell, from tcsh to sh, yet still work even on GNU/Linux, too.

Tested on OS X, OpenBSD and NetBSD in tcsh, and on Debian GNU/Linux in bash.

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With sed:

In tcsh on an OS X, the following sed snippet could be used together with printf, as neither sed nor echo handle \r in the special way like the GNU does:

sed `printf 's/\r$//g'` input > output

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With tr:

Another option is tr:

tr -d '\r' < input > output

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Difference between sed and tr:

It would appear that tr preserves a lack of a trailing newline from the input file, whereas sed on OS X and NetBSD (but not on OpenBSD or GNU/Linux) inserts a trailing newline at the very end of the file even if the input is missing any trailing \r or \n at the very end of the file.

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Testing:

Here's some sample testing that could be used to ensure this works on your system, using printf and hexdump -C; alternatively, od -c could also be used if your system is missing hexdump:

% printf 'a\r\nb\r\nc' | hexdump -C
00000000  61 0d 0a 62 0d 0a 63                              |a..b..c|
00000007
% printf 'a\r\nb\r\nc' | ( sed `printf 's/\r$//g'` /dev/stdin > /dev/stdout ) | hexdump -C
00000000  61 0a 62 0a 63 0a                                 |a.b.c.|
00000006
% printf 'a\r\nb\r\nc' | ( tr -d '\r' < /dev/stdin > /dev/stdout ) | hexdump -C
00000000  61 0a 62 0a 63                                    |a.b.c|
00000005
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