PHP exec（）输出缩短

Question

I have a PHP file that runs a node script using exec() to gather the output, like so:

$test = exec("/usr/local/bin/node /home/user/www/bin/start.js --url=https://www.example.com/");
echo $test;

It outputs a JSON string of data tied to the website in the --url paramater. It works great, but sometimes the output string is cut short.

When I run the command in the exec() script directly, I get the full output, as expected.

Why would this be? I've also tried running shell_exec() instead, but the same things happens with the output being cut short.

Is there a setting in php.ini or somewhere else to increase the size of output strings?

Answer 1

It appears the only way to get this working is by passing exec() to a temp file, like this:

exec("/usr/local/bin/node /home/user/www/bin/start.js --url=https://www.example.com/ > /home/user/www/uploads/json.txt");
$json = file_get_contents('/home/user/www/uploads/json.txt');
echo $json;

I would prefer to have the direct output and tried increasing output_buffering in php.ini with no change (output still gets cut off).

Definitely open to other ideas to avoid the temp file, but could also live with this and just unlink() the file on each run.

Answer 2

exec() only returns the last line of the output of the command you pass to it. Per the section marked Return Value of the following documentation:

The last line from the result of the command. If you need to execute a command and have all the data from the command passed directly back without any interference, use the passthru() function.

To get the output of the executed command, be sure to set and use the output parameter.

• https://www.php.net/manual/en/function.exec.php

To do what you are trying to do, you need to pass the function an array to store the output, like so:

exec("/usr/local/bin/node /home/user/www/bin/start.js --url=https://www.example.com/", $output);
echo implode("\n", $output);