[SOLVED] Passing columns position as input to AWK command

Issue

A script will transform csv file header positions A,C,B,D to A,B,C,D and output is variable VAR_INP will be used in awk to print and create new csv file.

VAR_INP="TMP1=$1 ; TMP2=$2 ; TMP3=$3 ; TMP4=$4 ; $1=TMP1 ;$3=TMP2 ;$2=TMP3 ;$4=TMP4 ;"

I need to use this VAR_INP as input command inside awk.

echo "A,C,B,D" > input.csv

awk 'BEGIN { FS=OFS","}
{
$VAR_INP 
print
}' input.csv

expected output

A,B,C,D

I am not getting desired results. its printing the input as it is.

it works only if i expand the VAR_INP and run manually

Please advise.

Solution

You could do it by letting the variable become part of the awk script, e.g.:

VAR_INP='TMP1=$1 ; TMP2=$2 ; TMP3=$3 ; TMP4=$4 ; $1=TMP1 ;$3=TMP2 ;$2=TMP3 ;$4=TMP4 ;'
awk -F, -v OFS=, '{'"$VAR_INP"'}1' input.csv

Output when input.csv contains A,C,B,D:

A,B,C,D

Answered By - Thor

Answer Checked By - Robin (WPSolving Admin)