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"
