What you said it does, in case that's what you want: 

perl -ne'print "$.\t$_" if /GRHL3/'

[download]

What it actually does (only the second field is checked for the pattern): 

perl -ane'print "$.\t$_" if $F[1] =~ /GRHL3/'

[download]

$. is in perlvar, and -n and -a are in perlrun.

In reply to Re: print if // line number? by ikegami
in thread print if // line number? by ZWcarp

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