FAQ 5.35 How do I close a file descriptor by number?


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5.35: How do I close a file descriptor by number?

If, for some reason, you have a file descriptor instead of a filehandle
(perhaps you used "POSIX::eek:pen"), you can use the "close()" function
from the "POSIX" module:

use POSIX ();

POSIX::close( $fd );

This should rarely be necessary, as the Perl "close()" function is to be
used for things that Perl opened itself, even if it was a dup of a
numeric descriptor as with "MHCONTEXT" above. But if you really have to,
you may be able to do this:

require 'sys/syscall.ph';
my $rc = syscall(&SYS_close, $fd + 0); # must force numeric
die "can't sysclose $fd: $!" unless $rc == -1;

Or, just use the fdopen(3S) feature of "open()":

open my( $fh ), "<&=$fd" or die "Cannot reopen fd=$fd: $!";
close $fh;


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