2 mawk pattern matching is probably too greedy as it fails when two paths on same line:
5 mawk: run time error: regular expression compile failed (missing operand)
6 /usr/lib/nullmailer' || -d '/usr/local/lib/nullmailer
7 FILENAME="check_mailq.pl" FNR=627 NR=627
10 --- nagios-plugins-2.0.1/plugins-scripts/check_mailq.pl~ 2014-04-21 14:33:35.000000000 +0300
11 +++ nagios-plugins-2.0.1/plugins-scripts/check_mailq.pl 2014-04-21 14:33:37.760719061 +0300
16 - elsif (-d '/var/lib/postfix' || -d '/var/local/lib/postfix'
17 - || -e '/usr/sbin/postfix' || -e '/usr/local/sbin/postfix')
18 + elsif (-d '/var/lib/postfix'
19 + || -d '/var/local/lib/postfix'
20 + || -e '/usr/sbin/postfix'
21 + || -e '/usr/local/sbin/postfix')
25 - elsif (-d '/usr/lib/exim4' || -d '/usr/local/lib/exim4'
26 - || -e '/usr/sbin/exim' || -e '/usr/local/sbin/exim')
27 + elsif (-d '/usr/lib/exim4'
28 + || -d '/usr/local/lib/exim4'
29 + || -e '/usr/sbin/exim'
30 + || -e '/usr/local/sbin/exim')
34 - elsif (-d '/usr/lib/nullmailer' || -d '/usr/local/lib/nullmailer'
35 + elsif (-d '/usr/lib/nullmailer'
36 + || -d '/usr/local/lib/nullmailer'
37 || -e '/usr/sbin/nullmailer-send'
38 || -e '/usr/local/sbin/nullmailer-send')