GETDTABLESIZE(3) Linux Programmer's Manual GETDTABLESIZE(3)
NAME
getdtablesize - get file descriptor table size
SYNOPSIS
#include <unistd.h>
int getdtablesize(void);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getdtablesize():
Since glibc 2.12:
/* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 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 at-
tributes(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 5.07 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/.
Linux 2020-06-09 GETDTABLESIZE(3)