Unix shells include Almquist shell (ash),Bourne shell (B shell, sh), C shell (csh), Bourne Again Shell (bash), Debian Almquist shell (dash), Korn shell (ksh), Public domain Korn shell (pdksh), MirBSD Korn shell (mksh), Z shell (zsh) etc. There are several ways to find out what shell we are using. Continue reading →

To block / unblock an IP address, you’d update iptables setting (root / sudoer only). Continue reading →

In Linux, vi is powerful to search and replace the text. Vi provides the :s (substitute) command for search and replace. Continue reading →

Several frequently used GET and POST commands in curl are listed here. Continue reading →

This post describes how to change / modify host name / hostname under Redhat / CentOS. Continue reading →

There are multiple ways to find files containing a text string. Here is one simple command (grep) to achieve the goal. Continue reading →

When you received a CentOS 6.5 system, you might find out that only PHP 5.3.3 is available.  Some research shows, PHP 5.3 is a bit faster than 5.4.x and 5.5.x. However, some CMS or Forum systems will require 5.4 and above version to run them. Continue reading →