Often two regexen are better than one. Possible strategy: search for the strings you want and set a flag. Also check for the string you don't want and forget about that file immediately if you find it. (You may optimize it not to try to match the "good ones" if one has already been found.) Print the name of the file if the flag is set.

Update: minimal example with glob. If you want/need to use File::Find or one of its relatives, then adapt as needed. Hack && improve at will.

# untested
FILE: for (glob '*.txt') {
    open my $fh, '<', $_ or
      die "$_: D'Oh! $!\n";
    my $found;
    while (<$fh>) {
        /green|red|blue/ and $found++ if !$found;
        next FILE if /green red blue/;
    }
    print if $found;  # $\ eq "\n"
}

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Or else if you trust in advance your files not to be huge, you may slurp in them all at once and simply

print if /green|red|blue/ and !/green red blue/;

But do not cargo cult that into a (bad) habit, slurping is generally not recommended.

In reply to Re: regexp exclude a string by blazar
in thread regexp exclude a string by Murcia

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