When I have restarting the postfix server I am facing the below error ::
postfix-out/master: fatal: open lock file pid/master.pid: cannot create file exclusively: Permission denied
I having a centos server.
You can use this command to fix permissions on postfix files and directories.
The file that controls these permissions is located here:
There may have been a stale master.pid file or or existing postfix process running, to clear these you could have done:
This file is created every time postfix starts.
In debian the file is created in /var/lib/postfix/master.lock, you have to looking for the directoyr of your postfix an check the permissions and the owners of it.