However I still see to be running the old Perl 5.8.8 version as outputted from perl -v. How do I 'activate' Perl 5.12.3 now?

You have to add $home/localperl/bin to your PATH environment variable before the path in which your current Perl is.

On this occasion I can recommend App::perlbrew, which makes it very easy to install custom perl versions and switch between them and the system perl.

Unfortunately perlbrew is not recognised either

I have also amended my PATH but perl -v still shows 5.8.8!!

Well, you must install perlbrew first. What does your new $PATH look like?

echo $PATH
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Perl 6 - second systems done right

Make sure that the new perl comes before the old one in the path. Also, your shell may have cached the location of perl and so not "see" the old one even though the $PATH has changed.

You can clear that cache with the hash command in bash, and you can see which perl executable comes first in the path with which perl.

You probably have both versions installed. The one installed using the OS's package manager is the one aliased to "perl" without qualification.

You should be able to run the desired version using a qualified name: try perl5.12.3 -v.

You might have it on a different path than the OS's installed version, too.

Linux 2.6.24.5-85.fc8 my PATH is

PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/usr/lib/ccache:/usr/local/b
+in:/usr/bin:/bin:/usr/X11R6/bin:/home/pats/bin
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command not found results from perl5.12.3 -v.

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

use Config;

Main( @ARGV );
exit( 0 );

sub Main {
    my $sep = $Config{path_sep};
    my $pat = 'export PATH=%s$PATH';
    $pat = 'set PATH=%s%%PATH%%'  if $sep eq ';' ;

    printf "$pat\n", join $sep, (
        uniq(
            grep length,
            grep defined,
            map { $Config{$_} }
            qw' installsitebin installvendorbin installbin '
        ),
      ),
      '';
}
sub uniq (@) {
    my %seen = ();
    grep { not $seen{$_}++ } @_;
}

__END__
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export PATH=/usr/bin:$PATH
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set PATH=c:\perl\5.12.2\bin\MSWin32-x86-multi-thread;c:\perl\site\5.12
+.2\bin;c:\perl\5.12.2\bin;%PATH%
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which bashrc should I edit?

[root@Gandalf bin]# find / -name bashrc
/root/perl5/perlbrew/etc/bashrc
/etc/bashrc
/usr/share/doc/bash-3.2/startup-files/bashrc
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The one in your home directory, i've seen .profile, .inputrc, .bashrc ...

Bah, that should be

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

use Config;

Main( @ARGV );
exit( 0 );

sub Main {
    my $sep = $Config{path_sep};
    my $pat = 'export PATH=%s$PATH';
    $pat = 'set PATH=%s%%PATH%%'  if $sep eq ';' ;

    printf "$pat\n", join $sep, (
        uniq(
            grep length,
            grep defined,
            map { $Config{$_} }
            qw'
            installsitebin
            installvendorbin
            installbin
            installsitescript
            installvendorscript
            installscript
            '
        ),
      ),
      '';
}
sub uniq (@) {
    my %seen = ();
    grep { not $seen{$_}++ } @_;
}
__END__
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the output od the latest code is

export PATH=/usr/bin:$PATH

I have added this line to both /root/perl5/perlbrew/ and etc/bashrc

however im still seeing Perl 5.8.8