Using If-Statement to assign Variable in awk

Question

I am trying to create an awk script file that takes an input file and converts the fourth column of information for the first three lines into a single row. For example, if input.txt looks like this:

XX YY val1 1234
XX YY val2 2345
XX YY val3 3456
stuff random garbage junk extrajunk
useless 343059 random3

I want to print the fourth column for rows 1, 2 and 3 into a single row:

1234 2345 3456

I was trying to do this by using if/else-if statements so my file looks like this right now:

#!/usr/bin/awk -f

{
    if ($1 == "XX" && $3 == "val1") 
    {
             var1=$4; 
    }  
    else if ($1 == "XX" && $3 == "val2") 
    {
             var2=$4; 
    }
    else if ($1 == "XX" && $3 == "val3") 
    {
             var3=$4; 
    }
}

END{ print var1,var2,var3

and then I would print the variables on one line. However, when I try to implement this, I get syntax errors pointing to the "=" symbol in the var2=$4 line.

EDIT

Solved, in my real file I had named the variables funky (yet descriptive) names and that was messing it all up. - Oops.

Thanks

Welcome to SO, special thanks for showing your efforts in form of code(keep it up). But your question is NOT clear, its always recommended to add sample of input/output too in your question, so please do add the same and let us know then. — RavinderSingh13
– RavinderSingh13, Commented Apr 13, 2020 at 18:39
Is it as simple as to remind that you need { braces ...} around those statements if they are in the main body of awk code? Otherwise you will get random syntax errors (random as in related to the version of awk...) — dawg
– dawg, Commented Apr 13, 2020 at 18:42
Post a minimal complete script that demonstrates your problem. — Ed Morton
– Ed Morton, Commented Apr 13, 2020 at 19:03
It was a simple mistake on my part in my real variable names! Thank you all! — AMD
– AMD, Commented Apr 13, 2020 at 19:16

karakfa · Accepted Answer · 2020-04-13 19:10:44Z

1

you can write something like this

$ awk '$1=="XX"{if($3=="val1") var1=$4
                else if($3=="val2") var2=$4
                else if($3=="val3") var3=$4}
        // .. do something with the vars ....

however, if you just want to print the fourth column of the first 3 lines

$ awk '{printf "%s ", $4} NR==3{exit}' ile
1234 2345 3456

answered Apr 13, 2020 at 19:10

karakfa

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Ed Morton · Accepted Answer · 2020-04-13 19:20:41Z

1

Try this instead:

#!/bin/env bash
awk '
$1 == "XX" { var[$3] = $4 }
END { print var["val1"], var["val2"], var["val3"] }
' "$@"

There's almost certainly a much simpler solution depending on your real requirements though, e.g. maybe:

awk '
{ vars = (NR>1 ? vars OFS : "") $4 }
NR == 3 { print vars; exit }
' "$@"

. For ease of future enhancements if nothing else, don't call awk from a shebang, just call it explicitly.

answered Apr 13, 2020 at 19:20

Ed Morton

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