In perl this is done using quotemeta, which you can also do using \Q...\E to make it happen on the enclosed string. You can drop the final \E if it coincides with the string end.

The .* at the beginning and end are useless (even if you use $&, you can just use the whole string there instead supposing it's still unchanged). And once these are gone, the s modifier becomes useless too.

So in the end you get:

if ($text =~ /\Q$stub/) {
    # Do something
}
[download]

Or, since you are basically just looking for a substring, you can use index:

if (index($text, $stub) >= 0) {
    # Do something
}
[download]

Yeah,

if (index($text, $stub) >= 0) {
    # Do something
}
[download]

was just what I was going to suggest. A regex may simply be too much of a tool. I've often wished I had a little electric typewriter for addressing envelopes, rather than going through monkeyshines trying to print envelopes and get the orientation, etc., correct. Simplest is best, sometimes.

if ($text =~ /.*\Q$stub\E.*/s)
{ 
  #do something
}
[download]

Is there any reason why you don't want to drop the

.*

from both ends of the regex ????

My understanding is that using:

if ($text =~ /$stub/s)
[download]

Without knowing more about your intentions, it would seem difficult to offer detailed fine tuning advice.

The problem is that this scalar $stub is volatile and it also contains a little bracket...

I believe that though he listed that bob(scalar), it should be bob[scalar] as the description lists. In this case it would be interpreted as a character class instead of a string. \Q and \E would backslash these brackets.

In it's current form, there's really no conflict unless the string is something like bob(??{print $hi}).



Who is Kayser Söze?
All code is untested unless I say so.

Except that the parens () will be used for grouping and capturing by the regex, and so won't match the literals in the string;

perl -e '$s = q|b(s)|; print  "without quotemeta" if $s =~ /$s/; print
+ "with quotemeta" if $s =~ /\Q$s\E/;'

with quotemeta
[download]

qq