use strict;
my $str = '// test /Users/zachhardesty/MEGA/ibm/webui/WEB_UI_CONTENT_REACT/src/modules/IdentitySources/Components/index.ts[1, 1]';
my $regex = qr/(?<!\/)(\/(?=\b).+)\[(\d+), (\d+)\]/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