Deleting active mails in the mailq in Postfix

There are several scripts to do that, but I found most of them are not clearing the active queued messages as the mail ids contain '*' at the end of the ID field. I have used cut -n to get the exact mail ID and delete them.

Following given command will delete mails from/to 'testuser@test.com' from the queue:

postqueue -p | grep "testuser@test.com" | cut -f 1 -d ' ' | cut -c-10 | xargs -n 1 postsuper -d








Following referrences are worth to read:

http://www.postfix.org/postsuper.1.html



http://www.bstar.de/2014/07/08/how-delete-single-mails-from-the-mail-queue-of-postfix-plesk/

Linux Performance Observability Tools

I found this image from Facebook (It seems facebook is not providing gossips only :-) which is very useful for Linux system administrators in finding issues in the systems.

I have downloaded the image from its original site (Site owner Brendan D. Gregg) and the original site http://www.brendangregg.com/linuxperf.html


A big thank to Brendan D. Gregg for publishing this.

iptables Issue in CentOS7

I had issues in enabling iptables in CentOS7. After following the post (link given below) I was able to resolve the issue I had with enabling iptables.

Error I got when I tried to enable iptables

server1#systemctl restart iptables.service
Failed to issue method call: Unit iptables.service failed to load: No such file or directory

Following is the screen shot of the answer received through the post http://stackoverflow.com/questions/24756240/how-can-i-use-iptables-on-centos-7