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regexbashperlsedsolaris

sed regex with alternative on Solaris doesn't work

Currently I'm trying to use sed with regex on Solaris but it doesn't work. I need to show only lines matching to my regex.

sed -n -E '/^[a-zA-Z0-9]*$|^a_[a-zA-Z0-9]*$/p'

input file:

grtad
a_pitr
_aupa
a__as
baman
12353
ai345
ki_ag
-MXx2
!!!23
+_)@*

I want to show only lines matching to above regex:

grtad
a_pitr
baman
12353
ai345

Is there another way to use alternative? Is it possible in perl? Thanks for any solutions.

Solution

  • With Perl

    perl -ne 'print if /^(a_)?[a-zA-Z0-9]*$/' input.txt

    The (a_)? matches a_ one-or-zero times, so optionally. It may or may not be there.

    The (a_) also captures the match, what is not needed. So you can use (?:a_)? instead. The ?: makes () only group what is inside (so ? applies to the whole thing), but not remember it.