Multi-process CLI scripts with PHP

I’ve been wanting to write a multi-process command line script in PHP for a while now, and tonight I finally got round to it. Proc_open() is really useful if you want to run a batch of commands simultaneously, such as querying the A records for multiple domain names, or running a bunch of whois commands.

Anyway, in the following example I’ll show you how to lookup the A records of a number of Google’s domain names in parallel:

You’ll notice there are two foreach loops. In the first we simply “launch” our commands, without waiting for any response from them. In the second, we iterate though and grab the output of each command in sequence until an end of file character is received.