printf "foo\nversion '1.2.36'\nbaz\n" | perl -pi -e 'if ($_ =~ m/version\s+.\d+[.]\d+[.](\d+)/) { my $v1 = quotemeta $1; my $v2 = $1 + 1; $_ =~ s/$v1/$v2/ }' foo version '1.2.37' baz