open $a, "/etc/passwd" or die "can't  open /etc/passwd: $!\n";
{
        local $/ = undef;
        $userdetails = <$a>;
        print ">>",$userdetails,"<<\n";
}
close($a); # this closes the filehandle
print "A>",$a ,"<\n";  # this prints a glob
# .... (assume that some lines of code lies here)
# ..

#########################################################
# in some other part of the program, How do I check whether
# the filehandle associated with the handle is still open?
# I have done it this way, if(defined fileno($a)),
# because fileno(filehandle) will return undef if there is
# no filehandle associated with it.
# Is any other ways exist to check the above problem?.
#########################################################