getdtablesize(3) - Linux manual page (original) (raw)

getdtablesize(3) Library Functions Manual getdtablesize(3)

NAME top

   getdtablesize - get file descriptor table size

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#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 top

   **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 top

   The current limit on the number of open files per process.

ERRORS top

   On Linux, **getdtablesize**() can return any of the errors described
   for [getrlimit(2)](../man2/getrlimit.2.html); see VERSIONS below.

ATTRIBUTES top

   For an explanation of the terms used in this section, see
   [attributes(7)](../man7/attributes.7.html).
   ┌──────────────────────────────────────┬───────────────┬─────────┐
   │ **Interface** │ **Attribute** │ **Value** │
   ├──────────────────────────────────────┼───────────────┼─────────┤
   │ **getdtablesize**()                      │ Thread safety │ MT-Safe │
   └──────────────────────────────────────┴───────────────┴─────────┘

VERSIONS top

   The glibc version of **getdtablesize**() calls [getrlimit(2)](../man2/getrlimit.2.html) and
   returns the current **RLIMIT_NOFILE** limit, or **OPEN_MAX** when that
   fails.

   Portable applications should employ _sysconf(SCOPENMAX)_ instead
   of this call.

STANDARDS top

   None.

HISTORY top

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

SEE ALSO top

   [close(2)](../man2/close.2.html), [dup(2)](../man2/dup.2.html), [getrlimit(2)](../man2/getrlimit.2.html), [open(2)](../man2/open.2.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 getdtablesize(3)