getdtablesize

NAME

getdtablesize - get file descriptor table size

LIBRARY

Standard C library (libc, -lc)

SYNOPSIS

#include <unistd.h>

int getdtablesize(void);

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 glibc 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).

STANDARDS

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)