Thank you very much , this helped alot. I am still having a bit of trouble with the script,it will not update the file, unless $line = $newline; is inside the while loop

  while ($line =~ / Name=(.*?) \s+ Password=(.*?) (?:\s+|$) /mgx)
    {
        my $name     = $1;
        my $password = $2;
        print "Enter the plain text password for $name, ",
              "password is currently '$password'\n";

        chomp(my $newpass = <>);
        print "You will now swap $password for password='$newpass'\n";
        print "Continue? (y/n)\n";
        chomp(my $answer  = <>);

        # Change the copy

    $newline =~ s{Password=\Q$password\E}{Password=$newpass} 
if $answer =~ /y/i;


    }
    $line = $newline;       # Update this line in the file
}

untie @array
    or die "Cannot untie file '$filename': $!";
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As I explained above, you can’t put the assignment $line = $newline; inside the while loop, because updating $line resets the /g match position to the beginning of the string, creating an infinite loop. I tested my code before posting, and when the assignment $line = $newline; occurs after (i.e., outside) the inner loop, the tied file is updated correctly.

I suspect your current problem is that the regex match is failing. In light of your subsequent post, it appears your data file never contains a string matching / Name=(.*?) \s+ Password=(.*?) (?:\s+|$) /mx. You will need to adapt the while loop regex to the actual format of the data in the input file. For example (untested):

while ($line =~ / < Node \.*? Name="(.*?)" Type=".*?" Descr=".*?" Icon
+=".*?" Panel=".*?" Username=".*?" Domain=".*?" Password="(.*?)" .*? >
+ /mgx)
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or just:

while ($line =~ / < Node \.*? Name="(.*?)" .*? Password="(.*?)" .*? > 
+/mgx)
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Update (25^th November, 2015): Changed / < \s* Name= to / < Node .*? Name= in each regex.

Hope that helps,

Athanasius <°(((>< contra mundum

Iustus alius egestas vitae, eros Piratica,

s{Password=\Q$password\E}{Password=$newpass} if $answer =~ /y/i;
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my $sentence = 'The quick brown fox jumped over the lazy dog';
my $substring = 'quick.*?fox';
$sentence =~ s{\Q$substring\E}{big bad wolf};
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#!/usr/bin/perl

use strict;
use warnings; 
use Tie::File;

my $filename = '/home/stain/Downloads/REMOTEopen.xml';

tie my @array, 'Tie::File', $filename || die "Cannot tie file $filenam
+e to array: $!";

foreach my $line (@array)
{
    my $newline = $line;    # Make a copy


        while ($line =~ / <Node \s+ Name="(.*?)" .*? Password="(.*?)" 
+.*? > /mgx)
        {
        my $name = $1;
        my $password = $2;
        print "Enter the plain text password for $name, ",
              "password is currently $password\n";

        chomp(my $newpass = <>);
        print "You will now swap $password for $newpass\n";
        print "Continue? (y/n)\n";
        chomp(my $answer = <>);

        # Change the copy

        $newline =~ s{$password}{$newpass} if $answer =~ /y/i;
    }
        $line = $newline; # Update this line in the file

}

untie @array
    or die "Cannot untie file '$filename': $!";
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Hello again cbtshare,

wrapping the old password with \Q\E means that it will remain unchanged ..., so why do \q\e instead of just doing s{$password}{$newpass}

The purpose of adding \Q to a regex is to prevent any “special” regex characters from having their special meanings. For example, if the data contains:

Password="abcde$"
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then without a \Q the $ will be interpreted to mean match the end of a line, which will cause the match to fail (unless abcde actually happens to come immediately before the end of a line, followed immediately by " at the beginning of the next line). But when preceded by a \Q, special characters like $, ., +, and * lose their special regex meanings and are treated as literal characters. That’s why, if there’s any possibility that a password may contain a character which the Perl regex engine considers to be “special,” it’s good practice to add \Q ... \E around the variable containing that password.

can you suggest how I could get it to update immediately to the file instead of waiting till the loop ends?

That depends on which loop you have in mind. As I explained above, the file can’t be updated within the inner (while) loop. However, the file is already being updated between each iteration of the outer (foreach) loop. You can see this by adding another <> as follows:

use strict;
use warnings; 
use Tie::File;

$| = 1;

my $filename = 'REMOTEopen.xml';

tie my @array, 'Tie::File', $filename
    or die "Cannot tie file $filename to array: $!";

for my $line (@array)
{
    my $newline = $line;

    while ($line =~ / < Node \s* Name="(.*?)" .*? Password="(.*?)" .*?
+ > /mgx)
    {
        my $name     = $1;
        my $password = $2;
        print "Enter the plain text password for $name, ",
              "password is currently $password\n";

        chomp(my $newpass = <>);
        print "You will now swap $password for $newpass\n";
        print "Continue? (y/n)\n";
        chomp(my $answer  = <>);

        $newline =~ s{\Q$password\E}{$newpass} if $answer =~ /y/i;
    }

    $line = $newline;

    print "Press <Enter> to continue...";
    <>;
}

untie @array
    or die "Cannot untie file '$filename': $!";
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Assuming a file named “REMOTEopen.xml” is present in the current directory and contains data like this:

<Node Name="MUN" Type="Connection" Descr="" Icon="mRemoteNG" Panel="Ge
+neral" Username="root" Domain="" Password="a/5pqLSsMnvRfylxdN6coiFTdc
+2+$">
</Node>
<Node Name="ubunugit" Type="Connection" Descr="" Icon="mRemoteNG" Pane
+l="General" Username="root" Domain="" Password="bBxKPKXIhw1wKEV9aEUN1
+yynoRGOWT$">
</Node>
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you can check the contents of the data file each time Press <Enter> to continue... is printed to the screen, and you should see that the file has indeed been updated as expected.

Hope that helps,

Athanasius <°(((>< contra mundum

Iustus alius egestas vitae, eros Piratica,

#!/usr/bin/perl

use strict; use warnings; use Tie::File;

my $filename = '/home/stain/Downloads/REMOTEopen.xml';

tie my @array, 'Tie::File', $filename or die "Cannot tie file $filenam
+e to array: $!";

foreach my $line (@array)
{
    my $newline = $line;    # Make a copy


         while ($line =~ / <Node \s+ Name="(.*?)" .*? Password="(.*?)"
+ .*? > /mgx)
        {
        my $name = $1;
        my $password = $2;
        print "Enter the plain text password for $name, ",
              "password is currently $password\n";

        chomp(my $newpass = <>);
        print "You will now swap $password for $newpass\n";
        print "Continue? (y/n)\n";
        chomp(my $answer = <>);

        # Change the copy

        #$newline =~ s{Password=\Q$password\E}{Password=$newpass} if $
+answer =~ /y/i;
        $newline =~ s{\Q$password\E}{$newpass} if $answer =~ /y/i;

    }
    $line = $newline; # Update this line in the file

}

untie @array
    or die "Cannot untie file '$filename': $!";
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