Join command combines lines from two files based on a common field. In the example below, we have two files – employee.txt and salary.txt. Both have employee-id as common field. So, we can use join command to combine the data from these two files using employee-id as shown below. $ cat employee.txt 100 Jason Smith 200 John Doe 300 Sanjay
Read moreSometime while debugging a shell script, you may not want to see either the standard output or standard error message. Use /dev/null as shown below for suppressing the output. Suppress standard output using > /dev/null This will be very helpful when you are debugging shell scripts, where you don’t want to display the echo statement and interested in only looking
Read moreFind is frequently used command to find files in the UNIX filesystem based on numerous conditions. Let us review some practice examples of find command. Syntax: find [pathnames] [conditions] How to find files containing a specific word in its name? The following command looks for all the files under /etc directory with mail in the filename. # find /etc -name
Read moreRegular expressions are used to search and manipulate the text, based on the patterns. Most of the Linux commands and programming languages use regular expression. This hack explains how to use most frequently used reg-ex operators in Grep command. Beginning of line ( ^ ) In grep command, caret Symbol ^ matches the expression at the start of a line.
Read moreGrep command is used to search files for a specific text. This is incredibly powerful command with lots of options. Syntax: grep [options] pattern [files] How can I find all lines matching a specific keyword on a file? In this example, grep looks for the text John inside /etc/passwd file and displays all the matching lines. # grep John /etc/passwd
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