| GETDTABLESIZE(3) | Library Functions Manual | GETDTABLESIZE(3) | 
getdtablesize —
#include <unistd.h>
int
  
  getdtablesize(void);
getdtablesize function is an equivalent of
  sysconf() with _SC_OPEN_MAX.
getdtablesize() function call appeared in
  4.2BSD.
Historically, each process had a fixed size descriptor table,
    which is guaranteed to have at least 20 slots. The entries in the descriptor
    table are numbered with small integers starting at 0. The call
    getdtablesize() used to return the size of this
    table. It doesn't make much sense these days because the size of the table
    is dynamic.
| January 5, 2012 | NetBSD 10.0 |