linux man page for getdtablesize

GETDTABLESIZE(2)					     Linux Programmer's Manual						  GETDTABLESIZE(2)

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 descrip-
       tor.

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.

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 getrlimit(2) and returns the current RLIMIT_NOFILE
       limit, or OPEN_MAX when that fails.  The libc4 and libc5 versions return OPEN_MAX (set to 256 since Linux 0.98.4).

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

COLOPHON
       This page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2010-09-20							  GETDTABLESIZE(2)