use strict;
use warnings;

my @corners;
$|++; #get correct order of print and die (STDOUT STDERR)


while(<DATA>){
    $_=~ s/\s+/ / ;
    chop $_;
    push @corners, $_ ;
    print "\n@corners\n";
    }

my $corner;

foreach(@corners){
    $corner=$_;
    &loading_tsc;
    }


sub loading_tsc{
print "DEBUG: loading_tsc received '@_'";
    chdir($corner) or die "\n $!\n";
    print "\n";
    print `pwd`;
    print "\n";
    }
    
__DATA__
AAA
BBB
CCC
DDD

##</code><code>##


AAA

AAA BBB

AAA BBB CCC

AAA BBB CCC DDD
DEBUG: loading_tsc received ''
 No such file or directory


##</code><code>##

    @corners = <DATA> ;
##</code><code>##

    foreach my $corner(@corners){...
##</code><code>##

    foreach my $corner(@corners){
               chomp $corner;          # we still need to chomp it..
               &loading_tsc ($corner); # better use of a sub.

    }


##</code><code>##

use Cwd;
    my $start_dir = getcwd;

...

sub loading_tsc{
    print "DEBUG: loading_tsc received '@_'";
    my $current_corner = shift;
    chdir($start_dir.'/'.$current_corner ) or die "\n $!\n";
    print "\n";
    print `pwd`;
    print "\n";
}

##</code><code>##

use File::Spec;

..

my $current_dir = File::Spec->rel2abs('.');

..

#in the sub now you can do:

my $path_to_go = File::Spec->catdir( $current_dir , $current_corner );
chdir $path_to_go or die "unable to chdir in $path_to_go\n";