getdtablesize - get file descriptor table size
#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
getdtablesize() returns the maximum number of files a process can have
open, one more than the largest possible value for a file descriptor.
The current limit on the number of open files per process.
On Linux,
getdtablesize() can return any of the errors described for
getrlimit(2); see NOTES below.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| getdtablesize () |
Thread safety |
MT-Safe |
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.
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.
close(2),
dup(2),
getrlimit(2),
open(2)