文件描述符

在n>或n>>中的n引用文件描述符。

Refers to the file descriptor .

对于每个open（）调用来说，都必须有一个使用完全相同标记和文件描述符的release（）调用。

For every open () call , there will be exactly one release () call with the same flags and file descriptor .

在顶层是打开的file对象，它由进程的文件描述符列表引用。

At the top is the open file object , which is referenced by a process 's file descriptor list .

select（）调用返回一个文件描述符列表，对于每个文件描述符至少注册了一个事件。

A select () call returns a list of file descriptors for which at least one registered event has occurred .

每个进程具有OPENMAX个文件描述符，您正尝试打开（OPENMAX+1个）文件。

Each process has OPEN_MAX file descriptors , and you 're trying to open ( OPEN_MAX + 1 ) files .

poll缓存管理一个可能很大的文件描述符集。

The pollcache manages a potentially large set of file descriptors .

每个poll（）调用都提供要poll的文件描述符列表。

Each poll () call provids a list of file descriptors to be polled .

这个系统调用需要shmopen（）返回的文件描述符，它返回指向内存的指针。

This system call requires the file descriptor from shm_open () and returns a pointer to memory .

extentextent是一种提高磁盘文件描述符效率的方法，它能够减少删除大型文件所需的时间等等。

Extents An extent is a way to improve the efficiency of on-disk file descriptors , reducing deletion times for large files , among other things .

在每个poll操作的开头，通过poll繁忙的文件描述符跟踪状态。

The state is tracked by polling busy file descriptors at the beginning of each poll operation .

关闭文件描述符或closefd可以是True或False。

The close file descriptor , or closefd , can be True or False .

当给定的文件描述符上没有数据可读时，它会反复执行read（）系统调用，这会浪费大量CPU周期。

It wastes a lot of CPU cycles just to iterate read () system calls when there is nothing to read on the given file descriptor .

此文件描述符在fork调用期间被复制，这就是两个进程都能对屏幕执行写入操作的原因。

This is duplicated during the fork , which is why both processes can write to the screen .

然后，应用程序用register（）调用向选择器注册通道（文件描述符）和感兴趣的操作。

The application then registers channels ( file descriptors ) and interested operations to the selector with a register () call on the channel .

空闲文件描述符的状态是已知的，因为在状态改变时会通知poll缓存服务。

The state of idle file descriptors is known since the pollcache service is notified once when it changes .

第一个参数fildes是函数open（）返回的文件描述符，用于指称具体设备。

The first parameter fildes is the open file descriptor returned from the function open (), referring to a specific device .

到这时，用户可以编写shell脚本，在变量中存储信息和导出信息，控制文件描述符，控制信号处理，使用for循环和case语句，以及其他大量功能。

Now , users could write shell scripts ; store and export information in variables ; control file descriptors ; control signal handling , for loops , and case statements ; and so much more .

shmunlink（）：根据（shmopen（）返回的）文件描述符，删除共享内存段。

Shm_unlink (): Deletes a shared memory region given a file descriptor ( returned from shm_open ()) .

另外，POSIXAPI使用简单的文件描述符执行读写，大家应该更熟悉。

Additionally , the POSIX API uses simple file descriptors for read and write and so should seem much more familiar .

Inotify提供一个简单的API，使用最小的文件描述符，并且允许细粒度监控。

Inotify provides a simple API that uses minimal file descriptors and allows fine granularity of monitoring .

Fexecve被用来exec文件描述符，现在可以在Linux中启用它。

Fexecve used to exec file descriptors , is now enabled in Linux .

当文件描述符的状态发生变化时，子系统通知poll缓存，这会在poll缓存中触发状态转换。

When the state of a file descriptor changes , the subsystem notifies the pollcache , which triggers a state transition in the pollcache .

但是，传统的poll方法有可伸缩性问题；它不太适合处理大量文件描述符。

The traditional polling method , however , has a scalability issue ; it does not scale well for a large number of file descriptors .

根本问题是，随着文件描述符数量的增加，每个poll操作所需的工作量会线性增加。

The fundamental problem is that the amount of work to be done for each poll operation scales linearly with the number of file descriptors .

poll一个对象需要两步：首先在文件描述符上建立一个持有计数，然后调用与这个文件描述符相关联的操作。

Polling an object involves first establishing a hold count on the file descriptor and then calling through the select fileop associated with the file descriptor .

如上所述，inotify使用文件描述符，允许程序员使用标准select或者poll函数来监视事件。

As noted above , inotify uses a file descriptor , allowing programmers to use standard select or poll functions to watch for events .

执行fork之后，父进程和子进程获得打开的所有文件描述符和数据值的拷贝，所以指针对于它们都是有效的。

After the fork , the parent and child have copies of all open file descriptors and data values , so the pointer works for both .

每个pccb根据文件描述符散列值放在poll缓存中。

Each pccb can be located in the pollcache based on a file descriptor hash .

其中的每个文件描述符由一个poll缓存控制块（pccb）表示。

Each file descriptor in the set is described by a pollcache control block & pccb .

例如，典型的读写操作可以在网络socket上执行（socket使用一个文件描述符表示，与一个普通文件一样）。

For example , typical read and write operations may be performed on a networking socket ( which is represented by a file descriptor , just as a normal file ) .