Troubleshooting

Q. How do I fix an error, while restarting Apache ~ Address already in use: make_sock: could not bind to port 80? A. If you are running SELinux disable temporary for port 80. Apache Address already in use: make_sock: could not bind to port 80 error and solution First make sure port 80/443 is not used by any other service or application with …

If you find any of the following errors below in your /var/log/exim_mainlog log file. The fix below should resolve these errors 2013-12-22 03:16:00 Failed to get write lock for /var/spool/exim/db/ratelimit.lockfile: timed out 2013-12-22 03:16:00 H=[190.235.210.104]:13468 temporarily rejected connection in "connect" ACL: ratelimit database not available To fix these error , the exim cache database on the server needs to be …

If you’re updating nagios, and/or you are trying to reschedule checks manually, and you get the error below: Error: Could not open command file ‘/usr/local/nagios/var/rw/nagios.cmd’ for update! Then it means that the permissions on the folder are messed up. Don’t bother setting up the permissions on the file itself, nagios.cmd,  since that file gets recreated very often, so: chown nagios.nagcmd …

On Unix operating systems, a zombie process or defunct process is a process that has completed execution but still has an entry in the process table, allowing the process that started it to read its exit status. It almost always means that the parent is still around. If the parent exited, the child would be orphaned and re-parented to init, …

Q. How do I install and configure NTP under CentOS Linux 5 server to synchronize the system clock? A. You can easily install NTP (Network Time Protocol, a means of transmitting time signals over a computer network) using yum command under Redhat or CentOS/Fedora core Linux. Procedure Login as the root user Type the following command to install ntp # …

Cron is a daemon that can be used to schedule the execution of recurring tasks according to a combination of the time, day of the month, month, day of the week, and week. This is how I install crond onto my CentOS server edition as it doesn’t seem to come preinstalled, this might not be true for other distributions and …

The Exim mail server has a lot of options/commands to find out the details of spammers easily from the command line. Click this link “Spam Check” to get more ideas. We can find out the mail queue details, spam mail sender details, spam mail counts etc from the link I mentioned above. Here is a script/piped-command to find out the …