print $file $_ if s/$LeftSide/$RightSide/eegi;

##</code><code>##

print $_ if s/$LeftSide/eval $RightSide/egi;

##</code><code>##

# main.pl

# all this is just a template that creates "run.pl"
use strict;
use warnings;

while(<DATA>){	
	print $_ if s/search_here/replace_here/gi;
}

__DATA__
(123),(456),(789)
(abc),(def),(ghi)

##</code><code>##

# prepare_run.pl

open my $file, '+<', 'main.pl'; #your original script we will replace keywords
open my $run, '+>', 'run.pl'; #newly created script that we will execute below

print "Enter left side of s///: ";
chomp(my $LeftSide = <STDIN>);

print "Enter right side of s///: ";
chomp(my $RightSide = <STDIN>);

while(my $line = <$file>){
print $run $line if $line !~ /.*search_here.*/ || /.*replace_here.*/;
print $run $line if $line =~ s/(.*)search_here(.*)/$1$LeftSide$2/ && 	$line =~ s/(.*)replace_here(.*)/$1$RightSide$2/;
}

close($file);
close($run);

system("run.pl"); #or whatever the the equivalent of your OS.

##</code><code>##

# run.pl, will be created after running "prepare_run.pl" while using "main.pl" as a template.

use strict;
use warnings;

while(<DATA>){	
	print $_ if s/\),\(/\)\n\(/gi;
}

__DATA__
(123),(456),(789)
(abc),(def),(ghi)

##</code><code>##

(123)
(456)
(789)
(abc)
(def)
(ghi)