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PerlFAQ Server 03-17-2011 04:00 AM

FAQ 5.35 How do I close a file descriptor by number?
 
This is an excerpt from the latest version perlfaq5.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

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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::open"), 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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