FAQ 7.0 How do I match a pattern that is supplied by the user?

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7.0: How do I match a pattern that is supplied by the user?

    Well, if it's really a pattern, then just use

        chomp($pattern = <STDIN>);
        if ($line =~ /$pattern/) { }

    Alternatively, since you have no guarantee that your user entered a
    valid regular expression, trap the exception this way:

        if (eval { $line =~ /$pattern/ }) { }

    If all you really want to search for a string, not a pattern, then you
    should either use the index() function, which is made for string
    searching, or if you can't be disabused of using a pattern match on a
    non-pattern, then be sure to use "\Q"..."\E", documented in perlre.

        $pattern = <STDIN>;

        open (FILE, $input) or die "Couldn't open input $input: $!; aborting";
        while (<FILE>) {
            print if /\Q$pattern\E/;
        close FILE;


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