php exec() 后台进程问题
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php exec() background process issues
提问by kylex
I'm trying to process a file in the background with the following command, but it does nothing.
我正在尝试使用以下命令在后台处理文件，但它什么也没做。
exec("php csv.php $file $user > /dev/null &", $output);
If I remove > /dev/null &then the file processes, but not in the background.
如果我删除，> /dev/null &则文件会处理，但不会在后台处理。
exec("php csv.php $file $user", $output);
Any ideas?
有任何想法吗？
回答by Emery King
Note:
笔记：
If a program is started with this function, in order for it to continue running in the background, the output of the program must be redirected to a file or another output stream. Failing to do so will cause PHP to hang until the execution of the program ends.
如果一个程序是用这个函数启动的，为了让它在后台继续运行，程序的输出必须重定向到一个文件或另一个输出流。如果不这样做，将导致 PHP 挂起，直到程序执行结束。
http://php.net/manual/en/function.exec.php
http://php.net/manual/en/function.exec.php
so:
所以：
exec("php csv.php $file $user > /dev/null &"); // no $output
回答by moodboom
Have you considered using screen? You can start up a screen session that runs in a detached process. Output will go to the screen session, which you can reattach to in another terminal while it is still running.
您是否考虑过使用屏幕？您可以启动在分离进程中运行的屏幕会话。输出将转到屏幕会话，您可以在另一个终端仍在运行时重新附加到该会话。
exec("screen -d -m -S my_php_session csv.php $file $user", $output);
