How to include tsv/csv header in bash script output

Question

I have thousands of .tsv files where I am extracting the rows where column 2 is equal column 6.

I can use the below bash script, but I could not append column names (header) in the output.

What is the way to include header?

for x in *.tsv; do
   awk '$2==$6' <"$x" >"$x.tmp"
   mv "$x.tmp" "$x"
done

fedorqui · Accepted Answer · 2015-12-04 11:31:38Z

2

If you want to print based on two conditions, say so:

awk 'FNR==1 || $2==$6' file

This will print those lines that either of these:

Also, note you don't need to loop with bash, awk can do it:

awk '(FNR==1 || $2==$6) {print > FILENAME".bk"}' *.tsv

answered Dec 4, 2015 at 11:28

fedorqui

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5 Comments

Beautiful! Exactly what I needed.Thanks

Also, How do you invert this equal condition? I mean, to extract the rows that are not equal.

@MAPK you can say $2 != $6.

Thanks! I am new to awk/bash. Sounds similar to perl/python or R with most regex and conditions.

@MAPK it is sooooo nice. Interesting reading: Idiomatic awk