Try this version of your first snippet, to understand almut's first point a little better:

#!/usr/bin/perl -w
use strict;

# replacing double back slash...
my $string1 = "-----\\---------";
print "The starting  value is: $string1\n";  # add this line

$string1 =~ s/"\\"/"\"/g;
print "The resulting value is: $string1\n";
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You'll see that your use of s/// didn't really change anything. So when you face a problem like this, it's good to print both the "before" and the "after". In terms of handling command line args from @ARGV, you might want to try some tests first with a script like this:

#!/usr/bin/perl

use strict;
use warnings;

print "Contents of ARGV:\n>=", join( "=<\n>=", @ARGV), "=<\n";
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Run that a few times with different patterns of interest as command-line args, and see what happens. It's really just a way of finding out what the shell is doing to the args before passing them on to the perl script, which is a useful thing to know. Then add some s/// operations to alter the args, and see how those work.