use strict;
my $str = '<td bgcolor="#EEEEEE" align="center"><input id="selectedUser12" type="checkbox" name="selectedUser" disabled value="sid759e0649e819999a3dc12a93ad2af5204a83f20600000000:cshah2op~~Admin%20Users" ></td>
<td bgcolor="#EEEEEE"> </td>
<td bgcolor="#EEEEEE">cshah2op </td>';
my $regex = qr/<td bgcolor="#EEEEEE" align="center"><input id="([-0-9a-zA-Z =~:#\"%>\/<]*) /mp;
my $subst = '$1 $2';
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