Dear monks: I have a text file which contains:

The variable is $var_one.

I think the following program should copy it to STDOUT, and expand variable names found in the file, but it causes an "uninitialized variable" error in the evaluation:

my $var_one;
sub copy_file {
  open(IFILE, "<afile");
  while($x = <IFILE>) {$x =~ s|(\$\w+)|$1|eeg; print $x};
  close(IFILE);
}

copy_file();
[download]

This works, by bringing the variable inside the sub:

my $var_one;
sub copy_file {
  my $var_one = $var_one;
  open(IFILE, "<afile");
  while($x = <IFILE>) {$x =~ s|(\$\w+)|$1|eeg; print $x};
  close(IFILE);
}
[download]

This works too, and finds the global variable:

my $var_one;
sub copy_file {
  my $x = "<p>The variable is $var_one.</p>";
  $x =~ s|(\$\w+)|$1|eeg; print $x;
}
[download]

If I evaluate only once, I get the name of the variable, from the file, as expected:

sub copy_file {
  open(IFILE, "<afile");
  while($x = <IFILE>) {$x =~ s|(\$\w+)|$1|eg; print $x};
  close(IFILE);
}
[download]

So... the expression s|(\$\w+)|$1|eeg fails only when the variable is outside the sub, and only when called from inside the while statement. How can I force the RE to find the global variable?

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