use strict;
my $str = '2800 Software (C2800NM-ADVIPSERVICESK9-M), Version 12.4(24)T8, RELEASE SOFTWARE (fc1)';
my $regex = qr/Version\s*(\S+?),/p;
my $subst = 'x';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html