You're probably declaring the variable with my within the sub, which means that the value you define is invisible outside that subroutine unless you do something to make it visible to code outside the subroutine. You have two straightforward options:

1. Declare the variable outside of any block (you can use my for this or make it a global; it will be modifiable by the subroutine.
2. have the subroutine return the value.

For stylistic reasons, I prefer the second, as it lets anyone else reading your code immediately know where to look to find out where the value's getting set. Sometimes this isn't appropriate, though. Here are examples:

# strategy 1

my $var;

# other stuff

sub mysub {
    # do stuff -- don't declare my $var here, though.  It will mask th
+e one you want to set.
    $var = "whatever"; # sets $var declared above to "whatever"
    
}
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# option 2

my $var = mysub();

sub mysub {
     # do stuff
     $var = "whatever";
     return $var; # return is optional here, but makes what's going on
+ explicit.
}
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HTH

perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>); 
+$rose = "smells sweet to degree $n"; *other_name = *rose; print "$oth
+er_name\n"'
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