Using awk with variable

Question

I am using this awk command to extract three rows from a text file.

awk 'BEGIN {FS="\t";OFS=","}; {print $1,$3,$10}' $FILENAME > $OUTPUT

I wish to specify the column numbers as a variable separately so it will be easier to modify in the future like this:

COLUMNS=$1,$3,$10
awk 'BEGIN {FS="\t";OFS=","}; {print $COLUMNS}' $FILENAME > $OUTPUT

However it pulls all columns into the output, not only the 3 I specified. How do I do this properly?

Your trapped by the shell quoting necessities/rules/limits. Try echo $COLUMNS and start getting enlightened. ;-) — alk
– alk, Commented Nov 8, 2015 at 16:13

bian · Accepted Answer · 2015-11-08 10:54:30Z

1

like this ?

$ more file
a,b,c,d,e
1,2,3,4,5

$ a='$1,$2,$NF'

$ awk -F, "{print $a}" file
a b e
1 2 5

answered Nov 8, 2015 at 10:54

bian

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1 Comment

@Am_I_Helpful: The proposal works. So why doesn't this answer the OP's question please?