The question of whether perl will return a string or number, which is thouroughly interesting, is a bit of a side issue.

What you seem to be attempting to do is change a lexically scoped variable from a different scope.

use strict;
use warnings;

#use vars ('$M','$N');
 
#  local $SIG{__WARN__} = sub { $N=24 };
  
  my $t_num = sub { $N=24 };
  printf "\nThe value of N is now %s %d %o\n",$N,$N,$N;

  $M = sprintf "%x", 41;
  printf "\nThe value of M is now %s %d %o\n",$M,$M,$M;

  my $t_var = sub { 
     $M = 42;
     # printf "\nThe value of M is now %s %d %o\n",$M,$M,$M;
     sub { $M };
  };
  
  printf "\nThe value of t_var is now %s %d %o\n",$t_var->(),$t_var->(
+),$t_var->();
  printf "\nThe value of M is now %s %d %o\n",$M,$M,$M;

=head1 output

Global symbol "$N" requires explicit package name at v42_13.pl line 10
+.
Global symbol "$N" requires explicit package name at v42_13.pl line 11
+.
...
Global symbol "$M" requires explicit package name at v42_13.pl line 23
+.
Global symbol "$M" requires explicit package name at v42_13.pl line 23
+.
Execution of v42_13.pl aborted due to compilation errors.

=cut

=head uncommented 'use vars ('$M','$N');' output

Use of uninitialized value $N in printf at v42_13.pl line 11.
Use of uninitialized value $N in printf at v42_13.pl line 11.
Use of uninitialized value $N in printf at v42_13.pl line 11.
The value of N is now  0 0
The value of M is now 29 29 35
The value of t_var is now CODE(0xxxxxxxxxx) dddddddd ddddddddddd
The value of M is now 42 42 52

=cut
[download]

If you change the scope then you can probably put your local pc repair shop on speed-dial. I would advise not doing this with environment variables.

_additional not sure about this really, though, I'd have thought if this was an issue here, there would have been some more responses of the kind. I may have misunderstood this a little.

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