But if you just gotta have executable code in the search pattern, try something like:

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my $s = qq{xxx\x0cyy\x0czzz};
 dd $s;
 ;;
 $s =~ s{ \Q@{[ chr 12 ]}\E }{}xmsg;
 dd $s;
"
"xxx\fyy\fzzz"

"xxxyyzzz"
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in the TMTOWTDI spirit I repet what I said in ChatterBox yesterday night, but I strongly suggest you to follow the ikegami's way to do it: it is direct, concise and reliable with no need of temp variable. If you have problem with hex values just put some comments above the regex as a cheatsheet: # hex \x0C  is chr(12) and so on.

What I proposed yesterday was:

 s/${\(chr(12))}//g;
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That is more a trick than a real solution, good to know. See Re: Using 'ord' in a regular expression for substitution where JavaFan originally proposed this solution.

L*

Works for me.

$ perl -e'
   my $String = "xxxchr12yyy";
   $String =~ s/chr(12)//g;
   CORE::say $String;
'
xxxyyy
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not the string 'chr12', the ascii character (12)...

Has anyone seen this sliced bread thing? I's better than... sliced... well... never mind...

But you told it to match the string chr12! You can't place code in a string literal and expect it to be executed.

You want any of the following:

s/\014//g;            # By octal
s/\x0C//g;            # By hex
s/\x{C}//g;           # By hex (leading zeros allowed)
s/\N{U+C}//g;         # By hex (leading zeros allowed)
s/\N{FORM FEED}//g;   # By name
s/\N{FF}//g;          # By alias
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You could also use the character literally.

my $ff = chr(12);
s/\Q$ff\E//g;
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PriNet:

You can't have arbitrary code in the left of a substitution regular expression. (If you use the e modifier, though, you can do so on the right side.)

So you either need to use interpolation:

$form_feed = chr(12);
$var =~ s/$form_feed//g;
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Or you can just specify the value using a hex or octal literal \x0c or \014:

$var =~ s/\014//g;
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...roboticus

When your only tool is a hammer, all problems look like your thumb.

TIMTOWTDI party ;-) These haven't been mentioned yet:

s/\f//g
s/(??{ chr 12 })//g
s/ (??{ quotemeta chr 12 }) //gx
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use v6;
$_ = chr(65); .say; s/<{chr(65)}>/B/; .say;" # outputs A B
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use v6;
$_ = chr(65); .say; s/{"here".say; chr(65)}/B/; .say;" # outputs A her
+e BA
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