Linux manual pages Section 3  

Name

getdtablesize — get file descriptor table size

Synopsis

#include <unistd.h>
int getdtablesize( void);  
 
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getdtablesize():
Since glibc 2.20:
_DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L) Glibc 2.12 to 2.19:
_BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L) Before glibc 2.12:
_BSD_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION

getdtablesize() returns the maximum number of files a process can have open, one more than the largest possible value for a file descriptor.

RETURN VALUE

The current limit on the number of open files per process.

ERRORS

On Linux, getdtablesize() can return any of the errors described for getrlimit(2); see NOTES below.

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
getdtablesize() Thread safety MT-Safe

CONFORMING TO

SVr4, 4.4BSD (the getdtablesize() function first appeared in 4.2BSD). It is not specified in POSIX.1; portable applications should employ sysconf(_SC_OPEN_MAX) instead of this call.

NOTES

The glibc version of getdtablesize() calls getrlimit(2) and returns the current RLIMIT_NOFILE limit, or OPEN_MAX when that fails.

SEE ALSO

close(2), dup(2), getrlimit(2), open(2)

COLOPHON

This page is part of release 5.11 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man−pages/.


  Copyright 1993 Rickard E. Faith (faithcs.unc.edu)

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Modified 2002-04-15 by Roger Luethi <rlhellgate.ch> and aeb