No issues here... 
#!/usr/bin/perl

use strict;
use warnings;

while (<DATA>) {
  if ( /do_add/ ) {
    print "Wow!  Got do_add - $_";
  } else {
    print "Awwww - no do_add - $_";
  }
}

__DATA__
do_taxes
do_things
do_add
do_wop

[download]
Output: 
C:\Perl>perl testdo.pl
Awwww - no do_add - do_taxes
Awwww - no do_add - do_things
Wow!  Got do_add - do_add
Awwww - no do_add - do_wop

[download]

In reply to Re^3: Regexp for word with underscore in the middle by Transient
in thread Regexp for word with underscore in the middle by klaun

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