On 2022-04-24 03:45, konsolebox wrote: > A command like this doesn't display data: > > tail -f /var/log/messages -n +1 | grep -e something --line-buffered | tail > > probably because the last tail waits for the pipe to terminate.
Since the data comes from a file, you can use the watch utility for procps, like this: watch "tail -n 50 /var/log/messages | grep -e something" Unfortunately, that will be blank if the last 50 lines don't contain any matches. Workaround: watch "rm watchfile ; tail -n 50 /var/log/messages | grep -e pattern > tmpfile ; if [ -s tmpfile ] ; then mv tmpfile watchfile ; fi ; cat watchfile"