Learning AWK Programming

AWK as a filter (reading input from the Terminal)

Filter commands can take their input from stdin instead of reading it from the file. We can omit giving input filenames at the command line while executing the awk program, and simply call it from the Terminal as:

$ awk  'program'

In the previous example, AWK applies the program to whatever you type on the standard input, that is, the Terminal, until you type end-of-file by pressing Ctrl + D, for example:

$ awk  '$2==50{ print }'apple 50apple 50banana 60litchi 50litchi 50mango 55grapes 40pineapple 60........

The line that contains 50 in the second field is printed, hence it's repeated twice on the Terminal. This functionality of AWK can be used to experiment with AWK; all you need is to type ...