Michael (a.k.a. Anonymous Monk),
It depends on what you mean by valid filehandle. If you want to see if the open worked, you could simply do this:

#!/usr/bin/perl -w
use strict;
my $Open_Ok;
if (open (FILE,"file.txt")) {
    $Open_Ok = "ok";
}
else {
    $Open_Ok = "not ok";
}
print "$Open_Ok\n";
[download]

Of course if you don't add any more to the program, you are going to get a warning about using FILE only once, but that is ok.

If on the other hand, you want to know if there is any data left in the file to read, you want to check out eof.

If you want to check to see if the file exists and is readable, then you want to check out perldoc -f -X - pay attention to -e and -r.

If you are interested in finding out if a read on the filehandle will result in a block, you should check out the 4 arg select

I hope this helps and cheers - L~R