Tools to manage firewall Packet filter rules in Linux Kernel is managed by an user-space application named iptables in CentOS and RedHat. Since CentOS 7,…
Update 2023: the practice outlined in this post has been outdated. This post is for archive ony. One of the reasons I prefer CloudFormation over…
Most of the text processing can be processed by awk and sed. Sed is non-interactive stream editor that allows you to specify all editing instructions…
Cron and anacron We all know cron is a job scheduler. Many admin uses crontab to manage scheduled task. It is also important to know…
These are the things quite confusing or abstract while I was at school but now makes lots of sense after many years working with different…
If the default installation has swap on, you will see it from block device list: Many installations require swap to be off for performance reasons…