getmypid()

(PHP 4, PHP 5, PHP 7)

获取 PHP 进程的 ID

说明

获取当前 PHP 进程 ID。

返回值

返回当前 PHP 进程 ID，或在错误时返回FALSE。

注释

进程 ID 并不是唯一的，所以他们是一个弱熵源。对安全性有依赖的上下文中我们不推荐依赖于 pid。

参见

• getmygid()获取当前 PHP 脚本拥有者的 GID
• getmyuid()获取 PHP 脚本所有者的 UID
• get_current_user()获取当前 PHP 脚本所有者名称
• getmyinode()获取当前脚本的索引节点（inode）
• getlastmod()获取页面最后修改的时间

The lock-file mechanism in Kevin Trass's note is incorrect because it is subject to race conditions.
For locks you need an atomic way of verifying if a lock file exists and creating it if it doesn't exist. Between file_exists and file_put_contents, another process could be faster than us to write the lock.
The only filesystem operation that matches the above requirements that I know of is symlink().
Thus, if you need a lock-file mechanism, here's the code. This won't work on a system without /proc (so there go Windows, BSD, OS X, and possibly others), but it can be adapted to work around that deficiency (say, by linking to your pid file like in my script, then operating through the symlink like in Kevin's solution).
#!/usr/bin/php