getdtablesize()函数是干什么的

昨天写守护进程的时候要关闭从父进程那里继承的文件，碰到了这个函数，结果我用的时候说我未定义，今天才发现写成了gettablesize()，把d落下了，唉！它返回所在进程的文件描述附表的项数，即该进程打开的文件数目。

下面是英文描述，很简练很好，不翻译了

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