"\b" Expects a transition between a "\w" and a \W", so it will not match the transition between the ")" and ")" in your "machine30" case.

If you know there is something that is not a "Word" character, immediately following the machine name, you can use: 

    m/\Q$machine\E\W/

[download]
to match all your cases.

            “PHP is a minor evil perpetrated and created by incompetent amateurs, whereas Perl is a great and insidious evil perpetrated by skilled but perverted professionals.”
        ― Jon Ribbens

In reply to Re: Parsing Issue while using Variable name in Pattern by NetWallah
in thread Parsing Issue while using Variable name in Pattern by perlavi

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