Use md5 -q for HashProgramOutput.sh, to show only the checksum.

[dim]

Summary

This option is supported on both BSDs and macOS, and ensures the command
also works if GNU coreutils are not installed.

[serge-sans-paille]

HashProgramOutput.sh

23

Why no silencing that one too?

[dim]

HashProgramOutput.sh

23

With the BSD (and macOS) md5 command, the -q option is not really "silencing", but it prints out only the checksum in that case:

-q      Quiet mode - only the checksum is printed out.  Overrides the -r option.

GNU coreutils md5sum does not have an equivalent option: you must always parse the standard output, and take the first printed field as the checksum.

Note that GNU md5sum indeed has a --quiet option, but its meaning is rather different: it can only be used in --check mode, and then its effect is that it does not show OK for each correctly verified input file.

[serge-sans-paille]

HashProgramOutput.sh

23

Then your change will make md5sum fail when the GNU version is used? I must be missing something :-)

[dim]

HashProgramOutput.sh

23

Yes, you are missing that I didn't change anything for GNU md5sum, only for the BSD/mac md5 command. :) Normally its output is something like:

% md5 foo
MD5 (foo) = d3b07384d113edec49eaa6238ad5ff00

but that makes it more difficult to parse out just the checksum. This is what the -q option is for.

[serge-sans-paille]

HashProgramOutput.sh

23

Got it! Thanks for the clarification, LGTM then :-)

HashProgramOutput.sh

if [ ! -x "$md5cmd" ]; then
     if [ ! -x "$md5cmd" ]; then
         echo "error: unable to find either 'md5sum' or 'md5'"
         exit 1
     fi
 fi
 
 mv $1 $1.bak
 if [ $is_md5sum = "0" ]; then
-    $md5cmd < $1.bak > $1
+    $md5cmd -q < $1.bak > $1
 else
     $md5cmd < $1.bak | cut -d' ' -f 1 > $1
 fi
 rm -f $1.bak