Sorry for the confusion:

my $enc_pass = shift ( @{ [ <$file> ] } );
[download]

Will simply take the first line within the file, whose handle is stored in the $file variable, treat the handle like a listed de-referenced array-ref and shift that first line into the $enc_pass variable.

For example, if your file contains:

ENCRYPTED_PASSWORD
[download]

when you:

print $enc_pass;
[download]

you will get the output:

ENCRYPTED_PASSWORD
[download]

For $gpg_out, that is the handle to the command line gpg call. Another method of this would be to use backticks such as:

my $gpg_output = `gpg --passphrase-fd 0 --decrypt --output oldfile new
+file`;
[download]

Simply enough, the backticks will automagically run the command specified, giving the output back to the $gpg_output variable.

Hope this all clarifies!