使用dev> null&运行exec()命令不起作用，但是dev> null起作用 [英] Running exec() command with dev>null & doesn't work, but dev>null does

问题描述

我有这个exec命令，它运行得很好，但是不会释放浏览器(即，存在php超时问题，但实际命令仍在运行):

I have this exec command which runs just fine, but doesn't free up the browser (ie. there is a php timeout issue, but the actual command continues to run):

exec("/usr/local/php53/bin/php csv.php $file $user > /dev/null");

当我运行ps auxw时，我看到了两个正在运行的进程:

When I run ps auxw I see these two running processes:

sh -c /usr/local/php53/bin/php csv.php /tmp/php9Pwu9e 294  >
/usr/local/php53/bin/php csv.php /tmp/php9Pwu9e 294

但是，当我运行下面的代码时，浏览器立即是免费的，但是命令不会继续运行:

However, when I run the code below, the browser immediately is free, but the command doesn't continue to run:

exec("/usr/local/php53/bin/php csv.php $file $user > /dev/null &");

当我运行ps auxw时，我看到一个正在运行的进程在16秒后死亡(并且似乎很快耗尽了内存并占用了大量CPU％):

When I run ps auxw I see one running process that dies after 16 seconds (and seems to eat up memory quickly and use a lot of CPU%):

/usr/local/php53/bin/php csv.php /tmp/php9Pwu9e 294

然后，该过程将在没有实际执行任何操作的情况下终止.不知道&符在做什么会导致这种情况.

Then the process dies without having actually done anything. Not sure what the ampersand is doing that would cause this.

当末尾没有&"号时，为什么还会出现sh -c的问题?我认为这可能表示某些事情，但不知道是什么.

Also why does sh -c appear when no ampersand is present at the end? I feel that this may be indicative of something, but have no idea what.

因为这一直作为答案出现， 我也尝试过:

Because this keeps cropping up as an answer, I have also tried:

exec("/usr/local/php53/bin/php csv.php $file $user > /dev/null 2>&1 &");

这证明了与上述相同的问题. 下面的代码可以运行，但不会释放浏览器.

Which demonstrates the same issue as mentioned above. The code below, does run, but does NOT free up the browser.

exec("usr/local/php53/bin/php csv.php $file $user > /dev/null 2>&1");

推荐答案

问题比我想象的要简单得多.问题是找不到$file(这是一个存储在/tmp目录中的上载文件).我不确定为什么，但是我想这与在后台进程获取文件之前将其销毁有关.

The issue was much simpler than I had thought. The problem was the $file (which was an uploaded file being stored in the /tmp directory) was not found. I'm not sure why, but I imagine it has something to do with the file being destroyed before the background process can get to it.

解决方案是将文件move_uploaded_file()固定到一个永久位置，然后使用该文件运行脚本.那行得通.

The solution was to move_uploaded_file() the file to a permanent location, and run the script with that file. That worked.

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