redhat 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);

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.

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).

CONFORMING TO
       SVr4, 4.4BSD (the getdtablesize function first appeared in BSD 4.2).

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

Linux 2.4							    2002-04-15							  GETDTABLESIZE(2)