Writing a AWK script by taking the input file as an argument

Question

I'm new to Linux, so this might be a relatively simple task but my research failed me. I want to write a awk script where it should iterate through a input file which has only one word per line and assign it to a variable, and I have to do some string operations on it. I'm quite confused with how to take the word on each line (by referencing the input file entered in the terminal) and assign it to a variable.

Answer 1

If each line has a single word on it, awk would put that word in $1 ("the first field"). You can then extract it from there and put it in a variable if you like, with var = $1. Regardless, you can do any string operation that you wish by operating on $1 (or var, if you assigned the value to that variable).

For example, assuming each word looks like word=otherthing and we'd like to output only otherthing:

awk '{ split($1, a, "="); print a[2] }' infile

or shorter,

awk -F '=' '{ print $2 }' infile

$2 is the second field on each line, and with -F '=' we tell awk that the fields are delimited by =.

You don't mention what it is you need to do, so I won't give more examples.

You may also write this as a script that a user can call directly:

#!/usr/bin/awk -f

BEGIN { FS = "=" }

{ print $2 }

This would be saved in a text file, made executable (with chmod +x script.awk), and then a user could call it with

./script.awk infile

... assuming the #!-line pointed to your awk binary.