Appending Text To the Existing First Line with Sed

Question

I have a data that looks like this (FASTA format). Note that in comes with block of 2 ">" header and the sequence.

>SRR018006
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNGN
>SRR018006
ACCCGCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

What I want to do is to append a text (e.g. "foo" in the > header) yielding:

>SRR018006-foo
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNGN
>SRR018006-foo
ACCCGCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

Is there a way to do that using SED? Preferably inline modifying the original file.

Answer 1

This will do what you're looking for.

sed -ie 's/^\(>.*\)/\1-foo/' file