Sorry for being pedant but we are opening files here, so - unless you mistype your file handle, - you can always close a filehandle. Or am I wrong?

No need to apologize for being pedantic :-). I can't think of a situation where close would fail on a plain old file on a local filesystem; for that, it's just habit. But networked filesystems, sockets, pipes, and so on can mess up close; besides, Always Check System Call Return Values is a good habit to get into.

According to man 2 close (FreeBSD, OpenBSD and OS X) the two cases are:

ERRORS
     Close() will fail if:

     [EBADF]            D is not an active descriptor.

     [EINTR]            An interrupt was received.
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</unecessarily complete information>

But agreed, always checking the return value from system calls is good practice (just like you should always check your optics before testing your high powered laser when that jerk Kent's around . . . </Real Genius>).

Update: Ooop, tilly is correct below. Perl's close is more akin to fclose(3) than close(2) and can return with errno of any of the errors from close(2) or fflush(3) (and fflush(3) in turn may set errno if an underlying write(2) failed).

That's actually not complete information since Perl's close is more complicated than the corresponding C call. In particular when you close a file in Perl it also flushes data to the filehandle, which can fail if the filesystem is full.

Would you like to get an error message when your file got truncated because the filesystem was full?

Thanks,
I sometimes need some help with my English. Besides I think the original request was rather lacking to understand that

my ( $a, $b, ... $z )
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is acutally an array. So it was my intention - and even though it was counter productive in the end - to avoid confucion of what is actually going on between open and close.
BTW, my choice for reading a file into an array still is File::Slurp which was discussed quite exhaustively recently in a thread i just cannot find right now.

Cheers,
PerlingTheUK

Just to be super-super pedantic: my ( $a, $b, ... $z ) is a list, not an array :-)