Suppress make rule error output

Solution 1:

Another way to suppress the make: error ... (ignored) output is to append || true to a command that could fail. Example with grep that checks for errors in a LaTeX log file:

undefined:
  @grep -i undefined *.log || true

Without the || true, make complains when grep fails to find any matches.

This works for all commands, not just mkdir; that's why I added this answer.

Solution 2:

The error is ignored already by the leading '-' on the command line. If you really want to lose the error messages from mkdir, use I/O redirection:

bin:
    -mkdir bin 2> /dev/null

You will still get the 'ignored' warning from make, though, so it might be better to use the option to mkdir that doesn't cause it to fail when the target already exists, which is the -p option:

MKDIR_P = mkdir -p

bin:
    ${MKDIR_P} $@

The -p option actually creates all the directories that are missing on the given paths, so it can generate a a number of directories in one invocation, but a side-effect is that it does not generate an error for already existing directories. This does assume a POSIX-ish implementation of mkdir; older machines may not support it (though it has been standard for a long time now).