getdtablesize

       #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
       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
       This  page  is  part of release 4.04 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                             2015-03-02                  GETDTABLESIZE(3)
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