CODEWITHSUNDEEP
shellawk
Kumar Sambhav Pandey
Kumar Sambhav Pandey

Reputation: 1743

Unexpected empty result from shell script that calls awk

Below is the sample shell script, Here the value of NF is coming Null instead of 9 (the output of expression on line 4)

#!/bin/bash
#set -x
VAR="The quick brown fox jumped over the lazy dog."
NF=`echo $VAR | awk '{PRINT NF}'`
echo "$NF"

Any thoughts?

Upvotes: 1

Views: 81

Answers (4)

Jotne
Jotne

Reputation: 41456

Here is one way to do it (using Here String). PS always double quote variable like this "$var"

NF=$(awk '{print NF}' <<< "$var")

Upvotes: 1

Tom Fenech
Tom Fenech

Reputation: 74635

Others have explained what was wrong with your code. I would like to suggest another way to count the number of words:

var="The quick brown fox jumped over the lazy dog."
wc -w <<<"$var"

Or on older shells:

echo "$var" | wc -w

Upvotes: 1

Chirag Bhatia - chirag64
Chirag Bhatia - chirag64

Reputation: 4516

The command you're looking for is print, not PRINT. Awk is case-sensitive.

Also, it is recommended to use the following command substitution: $(...) instead of backticks (`).

So in your case:

NF=$(echo $VAR | awk '{print NF}')

Upvotes: 2

200_success
200_success

Reputation: 7582

AWK is case-sensitive. You want the function print.

By writing PRINT NF instead, AWK interprets that as the names of two variables, concatenated. PRINT has an empty value; NF has the value "9". You didn't ask it to do anything with the result (such as printing it), so the AWK script produces no output for that line of input.

Upvotes: 3

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