getdtablesize(3)

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).
Interface | Attribute | Value
 | Thread safety | MT-Safe

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

Portable applications should employ sysconf(_SC_OPEN_MAX) instead of this call.

STANDARDS
None.

HISTORY
SVr4, 4.4BSD (first appeared in 4.2BSD).

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