In this post we learn to manage environment variables in the shell. These variables are often needed by applications. $ dollar sign Another important character interpreted by the shell is the dollar sign $. The shell will look for an environment variable named like the string following the dollar sign and replace it with the … Read more
In this post we put more than one command on the command line using control operators. We also briefly discuss related parameters ($?) and similar special characters(&). ; semicolon You can put two or more commands on the same line separated by a semicolon ; . The shell will scan the line until it reaches … Read more
arguments One of the primary features of a shell is to perform a command line scan. When you enter a command at the shell’s command prompt and press the enter key, then the shell will start scanning that line, cutting it up in arguments. While scanning the line, the shell may make many changes to … Read more
This post briefly tells the history of Unix and where Linux fits in. 1969 All modern operating systems have their roots in 1969 when Dennis Ritchie and KenThompson developed the C language and the Unix operating system at AT&T Bell Labs.They shared their source code (yes, there was open source back in the Seventies) … Read more
Asterisk Gateway Interface (AGI) The Asterisk dialplan has evolved into a simple yet powerful programming interface for call handling. However, many people, especially those with a prior programming background, still prefer implementing their custom call handling in a different programming language. Using another programming language may also allow you to utilize existing code for integration … Read more
IPTABLES : Introduction to Linux Firewall Linux is the most-used open source operating system. Managing network traffic is one of the toughest jobs to deal with. For this, we must configure the firewall in such a way that it meets the system and users requirements without leaving the system vulnerable. The default firewall in most of the Linux distributions is IPTables. IPTables is … Read more
Find All Sudo Users In CentOS linux As a linux administrator, sometimes you need to how many super users and normal users are there in a system. So you need to find all sudo users in a centos (linux) system. However, there are chances that sometimes we need to give a temporary sudo access to a … Read more
Find Files and Directories Based on Size in Linux In Unix-like and some other operating systems, find is a command-line utility that searches one or more directory trees of a file system, locates files based on some user-specified criteria and applies a user-specified action on each matched file. To find all 50MB files, use. # find / … Read more
Find Files and Directories Based on Modification Time in Linux In Unix-like and some other operating systems, find is a command-line utility that searches one or more directory trees of a file system, locates files based on some user-specified criteria and applies a user-specified action on each matched file. Find Last 50 Days Modified Files … Read more
Search Files Based On Owners and Groups in Linux In Unix-like and some other operating systems, find is a command-line utility that searches one or more directory trees of a file system, locates files based on some user-specified criteria and applies a user-specified action on each matched file. To find all or single file called testdata.txt under / root … Read more