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# 1  
Old 11-06-2012
tail and log rotation

Need some suggestion with an old problem form a thread here:

Since my log is large, I did get help to make a line that splits the log into two parts
tail -f syslog | awk '!/snmpd|ntpd|reject/{print | "tee newlog"}'

(change from daemon.log to syslog)

Problem is that tail seems to stop and does not update the log file.

I then made a script that looked at the "newlog" and if it did not get updated in 3 hour, restarts the tail.
Its not a good solution, since I do loose 3 hour of data.

Recently I did see some post that tail have this problem with log rotate.
When syslog rotates to syslog.1, tail stops getting data, since it does not understand that it need to look at the new file.

I made a new script that restarts the tail if syslog.1 gets updated:
while [ 1 ]
file_now=$(ls -l /var/log/syslog.1 | awk '{print $8}')

if [ "$file_start" != "$file_now" ]; then
        file_start=$(ls -l /var/log/syslog.1 | awk '{print $8}')
        tail -f /var/logsyslog | awk '!/snmpd|ntpd|reject/{print | "tee newlog"}'

sleep 60

Is this a good solution, or you guys having a better solution for this?
# 2  
Old 11-06-2012
If you are on Linux or have GNU coreutils available, you can use

tail --follow=name filename

When logrotation happens, you will see a message like

tail: filename: No such file or directory
tail: `filename' has appeared;  following end of new file

You can redirect stderr to /dev/null if you do not want to see this message.
This User Gave Thanks to hergp For This Post:

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