Shell Programming and Scripting

Good Morning,

i ran into some trouble this morning while 'improving' my monitoring stuff. i would like to get a warning when the number of mails sent (outbound) by postfix is above a certain number. so far, so easy. to test that i simply put

Code:

cat /var/log/mail.info | grep 'to=<' | grep -v -e 'relay=dovecot\|relay=127*'

in the bash to rule out every line from amavis or incoming mail or locally sent stuff. that works like a charm and gives me exactly what i want. the same works with

Code:

tail -100 /var/log/mail.info | grep 'to=<' | grep -v -e 'relay=dovecot\|relay=127*'

and here is my problem: it completely failes me with

Code:

tail -f /var/log/mail.info | grep 'to=<' | grep -v -e 'relay=dovecot\|relay=127*'

but thats what i would prefer to use for 'real time' stuff. so how can i trust my numbers?

I am aware that i can go through the Logs, starting with the line 'last seen' and thats what Zabbix does anyway but i wonder why it does not work with the '-f' option ?

Can someone give me a push in the right direction here?

For threads started in the Shell Programming and Scripting forum, it always helps if you tell us what operating system and shell you're using.

In what way is the pipeline using tail -f not working.

We have to assume that you now that tail -f will never end and will continue reading from /var/log/mail.info forever, and the greps following that in your pipeline will continue processing data from that file as new lines are written to that file until something external to your pipeline terminates one of the processes in your pipeline. If you don't want the pipeline to run forever waiting for additional data to be written into that file, you shouldn't be using tail's -f option.