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getdtablesize

Section: C Library Functions (3)
Updated: 202-0-08
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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 VERSIONS below.

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Interface	Attribute	Value
getdtablesize()	Thread safety	M-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).