How do I test (in one line) if command output contains a certain string? In one line of bash, how do I return an exit status of 0 when the output of /usr/local/bin/monit --version doesn't contain exactly 5.5 and an exit status of 1 when it does? ! /usr/local/bin/monit --version | grep -q 5.5 (grep returns an exit-status of 0 if it finds a match, and 1 otherwise. The -q option, "quiet", tells it ..