getdtablesize(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

GETDTABLESIZE(3)        Linux Programmer's Manual       GETDTABLESIZE(3)

NAME         top

       getdtablesize - get file descriptor table size

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 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); see NOTES below.

ATTRIBUTES         top

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

       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             Attribute     Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │getdtablesize()                       │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO         top

       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         top

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.11 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                          2021-03-22               GETDTABLESIZE(3)