Linux
2016-03-15
man-pages
Linux kernel and C library user-space interface documentation
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 attributes(7).
| Interface | Attribute | Value |
| 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
getdtablesize() is implemented as a libc library function. The glibc version calls getrlimit(2) and returns the current RLIMIT_NOFILE limit, or OPEN_MAX when that fails.
