getdtablesize

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

NAME
       getdtablesize - get file 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:
               /* Glibc since 2.19: */ _DEFAULT_SOURCE
                   || /* Glibc versions <= 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 NOTES below.

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

       +----------------+---------------+---------+
       |Interface       | Attribute     | Value   |
       +----------------+---------------+---------+
       |getdtablesize() | Thread safety | MT-Safe |
       +----------------+---------------+---------+
CONFORMING TO
       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
       getdtablesize() is implemented as a libc library function.   The  glibc
       version calls getrlimit(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
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       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                             2016-03-15                  GETDTABLESIZE(3)
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