I would like to do the following to monitor for a pattern in a log file:
tail -f ./app.log | grep "My Pattern: .*" >> ./MyPattern.txt &
This is working fine until the
app.log reaches 500MB and it is moved to be
app-2015-10-28.0.log and a new
app.log is created. When this happens the
tail -f will stop working. Stopping and running the same command again will work, but in between stopping and starting, the pattern that appears in between the restarting may be missed.
Another condition of rolling is when it is 00:00. The same rolling will happen even when the log is < 500MB.
Log rolling is done at application level and we cannot control that part.
How can we detect the log has been rolled, without missing the patterns of interest?