getdtablesize(3) — Linux manual page

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | VERSIONS | STANDARDS | HISTORY | SEE ALSO | COLOPHON

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); see VERSIONS below.

ATTRIBUTES         top

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

VERSIONS         top

       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         top

       None.

HISTORY         top

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of the man-pages (Linux kernel and C library
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Linux man-pages 6.9.1          2024-06-16               getdtablesize(3)