Question

system("php ./somescript.php $something >/dev/null &");

I’m new to PHP and I am deciphering someone else’s code and can’t figure out what this code is doing. I looked at the system documentation here so I understand that it will execute the PHP script in somescript.php, and that $something is a parameter passed to that script…but after that I’m lost.

Also, what part of the script does $something get passed to? How does it know what function in somescript.php to call first?

Answer 1

It’s basically running the ./somescript.php program, with $something as a command-line parameter.

It explicitly ignores the output by routing it to the null device.

And it runs it in its own shell and doesn’t wait for it to finish (that’s the & bit on the end).

I assume that somescript.php is a program that runs some kind of background task. It probably takes a bit of time to run, but your main program doesn’t need to know about the results of that task, so it doesn’t need to wait for it to finish.

[EDIT]

$something is passed into the program as a command-line argument. When PHP is called from the command line, the arguments are populated into the $argv array.

See the PHP manual for more info:

• http://php.net/manual/en/reserved.variables.argv.php
• http://php.net/manual/en/features.commandline.php