I think it's easier and more efficient to switch the loops.

for (values %copy) {
    1 while                              # repeat till no replacement 
+left
        s/^($pattern)/$h_orig->{$1}/g; 
}

[download]

But I have trouble to come up with a test case covering the complicated implications. ( Update Anyone? ) 

use strict;
use warnings;
use Data::Dump qw/pp dd/;

my $h_orig =
  {
  '/a/b/c/dt/data/SUSE/tool/0.9.0' => '/a/b/c/dt/tools/SUSE/tool/0.9.0
+',
  '/nfs/us' => '/usr/bin',
  '/a/b/c' => '/nfs/us'
  };


my $pattern = join "|", map quotemeta, keys %$h_orig;

my %copy = %$h_orig;

for (values %copy) {
    1 while s/^($pattern)/$h_orig->{$1}/g; 
}

pp $h_orig, \%copy;

[download]

-*- mode: compilation; default-directory: "d:/tmp/pm/" -*-
Compilation started at Sun Feb  6 15:59:06

C:/Strawberry/perl/bin\perl.exe -w d:/tmp/pm/replace_pat2.pl 
(
  {
    "/a/b/c" => "/nfs/us",
    "/a/b/c/dt/data/SUSE/tool/0.9.0" => "/a/b/c/dt/tools/SUSE/tool/0.9
+.0",
    "/nfs/us" => "/usr/bin",
  },
  {
    "/a/b/c" => "/usr/bin",
    "/a/b/c/dt/data/SUSE/tool/0.9.0" => "/usr/bin/dt/tools/SUSE/tool/0
+.9.0",
    "/nfs/us" => "/usr/bin",
  },
)

Compilation finished at Sun Feb  6 15:59:06

[download]

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to Re^3: Replacing substrings with links by LanX
in thread Replacing substrings with links by ovedpo15

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