Home » Server Managment

Server Managment

Fixing time drift in the servers (syncing with time servers)

Sometimes the clock in the system may shows some drift ( lagging or leading) in time.  We can fix this by adjusting the tick rate in the server. 1. Compare the system time with that of any timeserver. You can use any of  the following command for this. rdate -p rdate.cpanel.net ;date OR rdate -p rdate.darkorb.net ;date Here rdate prints …

Read More »

Exim Error: Ratelimit database not available

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 …

Read More »

Error: Could not open command file ‘/usr/local/nagios/var/rw/nagios.cmd’ for update!

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 …

Read More »

How to install cron (crond, crontab)

Are you looking for crontab on a new install of CentOS 5? Well if you do a custom installation and don’t select anything then it will not be installed by default. In order to install it there just needs to be one package installed. See the below commands to install and setup crontab. Use this command to install crontab, start …

Read More »

How To Create A RAID-1 Setup On A CentOS/RedHat 6.0 Server

  This tutorial is for turning a single disk CentOS 6 system into a two disk RAID1 system. The GRUB bootloader will be configured in such a way that the system will still be able to boot if one of the hard drives fails (no matter which one).   NOTE: Everything has to be done as root: su - enter …

Read More »

Linux Centos 6 Change Server Hostname

I am a new CentOS Linux server user. How do I change hostname on CentOS Linux? How can I change server hostname on CentOS Linux  6? You need to use the following commands to set or view current hostname, domain name and/or FQDN (Fully Qualified Domain Name): dnsdomainname command : Display the system’s DNS domain name. hostname command : Show or …

Read More »

Linux / UNIX: Create Large 1GB Binary Image File With dd Command

How do I create 1 GB or 10 GB image file instantly with dd command under UNIX / Linux / BSD operating systems using a shell prompt? You can use dd command to create image files for network or file system testing. First, make sure you’ve sufficient disk space to create a image file using dd:   $ df -H …

Read More »