getdtablesize()函數是幹什麼的

昨天寫守護進程的時候要關閉從父進程那裡繼承的檔案，碰到了這個函數，結果我用的時候說我未定義，今天才發現寫成了gettablesize()，把d落下了，唉！它返回所在進程的檔案描述附表的項數，即該進程開啟的檔案數目。下面是英文描述，很簡練很好，不翻譯了
getdtablesize()

Get the size of the file descriptor table

Synopsis:

#include <unistd.h>

int  getdtablesize( void );

Library:

libc

Use the -l c

option to
qcc

to link against this library.
This library is usually included automatically.

Description:

Each process has 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 getdtablesize()
returns the
size of this table.

This function is equivalent to
getrlimit()

with the RLIMIT_NOFILE
option.

Returns:

The size of the file descriptor table.

Classification:

Legacy Unix

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes