Please always use strict; use warnings; and declare your variables.

You don't check the success of the second open call. If the open() fails, there will be no lines in @fp0 (same if the file exists but is empty), and $fp will be undef.

You can also use autodie to prevent such errors.

Perl 6 - second systems done right

In reply to Re: "Use of uninitialized value" even though the value is defined by moritz
in thread "Use of uninitialized value" even though the value is defined by mandrake00

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