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



NAME
       getdtablesize - get descriptor table size

SYNOPSIS
       #include <unistd.h>

       int getdtablesize(void);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getdtablesize():
           Since glibc 2.12:
               _BSD_SOURCE ||
                   !(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
           Before glibc 2.12:
               _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

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
   Multithreading (see pthreads(7))
       The getdtablesize() function is thread-safe.

CONFORMING TO
       SVr4, 4.4BSD (the getdtablesize() function first appeared in 4.2BSD).  It is not specified
       in POSIX.1-2001; portable applications should employ sysconf(_SC_OPEN_MAX) instead of this
       call.

NOTES
       getdtablesize()  is implemented as a libc library function.  The glibc version calls getr‐
       limit(2) and returns the current RLIMIT_NOFILE limit, or OPEN_MAX when that fails.

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

COLOPHON
       This page is part of release 3.74 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 http://www.kernel.org/doc/man-pages/.



Linux                                       2014-08-19                           GETDTABLESIZE(3)