Hi Richard,
Richard Retanubun wrote:
> /bin/dash -c "pgrep -f /usr/sbin/atftpd"; echo $?
> -vs-
> /bin/bash -c "pgrep -f /usr/sbin/atftpd"; echo $?
>
> The dash version returns the PID of the grep itself and thus always succeeds.
> The bash version works as expected.
As the pgrep(1) manual explains, the running pgrep or pkill process
will never report itself as a match. However, when running pgrep
through dash, it reports the process id of the shell executing pgrep,
while the bash version and recent dash versions optimize "sh -c
'single command'" to
sh -c 'exec pgrep -f /usr/sbin/atftpd'
so there is no shell process left to report.
If that "exec" is specified explicitly, the result is the same in both
shells.
Hope that helps,
Jonathan
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