AWK as a Unix command line

This is the most-used method of running AWK programs. In this method program, AWK commands are given in single quotes as the first argument of the AWK command line, as follows:

$ awk  'program' input file1 file2 file3 .......fileN

Here, program refers to the sequence of pattern-action statements discussed earlier. In this format, the AWK interpreter is invoked from the shell or Terminal to process the input line of files. The quotes around program instruct the shell not to interpret the AWK character as a special shell character and treat the entire argument as singular, for the AWK program not for the shell. It also enables the program to continue on more than one line.

The format used to call the AWK program from inside of a shell script is the same one we used on the Unix/Linux command line. For example:

$ awk  '{ print }' empinfo.txt /etc/passwd 

The preceding command will print every line of the empinfo.txt file, followed by the lines of the /etc/passwd file on your system, as follows:

Jack 9857532312 jack@gmail.com hr 2000 5
Jane 9837432312 jane@gmail.com hr 1800 5
Eva 8827232115 eva@gmail.com lgs 2100 6
amit 9911887766 amit@yahoo.com lgs 2350 6
Julie 8826234556 julie@yahoo.com hr 2500 5
at:x:25:25:Batch jobs daemon:/var/spool/atjobs:/bin/bash
avahi:x:481:480:User for Avahi:/run/avahi-daemon:/bin/false
avahi-autoipd:x:493:493:User for Avahi IPv4LL:/var/lib/avahi-autoipd:/bin/false
bin:x:1:1:bin:/bin:/bin/bash
daemon:x:2:2:Daemon:/sbin:/bin/bash
games:x:12:100:Games account:/var/games:/bin/bash
man:x:13:62:Manual pages viewer:/var/cache/man:/bin/bash
messagebus:x:499:499:User for D-Bus:/run/dbus:/bin/false
......................
...................... till last line in /etc/passwd