CODEWITHSUNDEEP
phpbashspawn
InterLinked
InterLinked

Reputation: 1403

How to synchronously spawn another PHP script from within a PHP script?

I have a terminal application that is currently written in Bash, about 20,000 SLOC. One thing that I like about the way that it's set up is that it is quite modular. Different components are spread across different files, which can be executed at run time. This means that parts of the system can be "hot swapped" or updated during runtime without needing to kill the main program and re-execute it.

The disadvantage is there is a lot of database I/O, which makes it super janky since Bash is really not suited for this. Currently, it interfaces with HTTP APIs which spawn PHP.

I'd like to rewrite it natively in PHP (CLI) to cut out the middleman layer, so the application can communicate directly with the database, making maintenance much easier. One problem I've been pondering though is how to replicate the same modularity with Bash. With Bash, if I call script A, and I make a change to script B, and then I enter script B from script A (assuming it's in a conditional block somewhere, not right at the top of the file), the changes are picked up without needing to re-execute script A, since script B isn't interpreted until it gets executed.

I'm struggling to figure out how to achieve this with PHP. For instance, this will not work:

include('script.php');

The reason is that includes are all executed when the script is interpreted, not when it is executed at run time.

A similar question has been asked already, but it doesn't specifically address this aspect, just how to launch another script in general. I want to basically be able to spawn the script anew at runtime, when the application decides it should be executed. shell_exec and passthru seem to be all that is built into PHP that would be similar, but I'm not sure this is right since that's just spawning another system shell and doing it there, so it's not as "direct" as with Bash.

What would be the proper equivalent in PHP of this in Bash:

if [ "$x" = "3" ]
then
   ./launchscriptnow.sh
fi

The user should now be executing launchscriptnow.sh. Remember that this is an interactive application, so it's not just doing something and returning a value. The user could be here for 2 seconds, 5 minutes, or an hour.

So that ./launchscriptnow.sh is only interpreted when the code gets to that line, not when the parent script itself is interpreted? Is this kind of thing purely a shell construct or is there an equivalent to this?

Upvotes: 0

Views: 191

Answers (2)

Teson
Teson

Reputation: 6736

Against all recommendations you could:

$script = file_get_contents('module_b.php');
$script = str_replace('<' . '?php', '', $script);
$script = str_replace('?' . '>', '', $script);
eval($script);

Upvotes: 1

nusbaum
nusbaum

Reputation: 36

I'm don't understand your concern about "when the script is interpreted" vs "when the script is executed"? I have a number of scripts that use a variable name for the script to be included and make that decision right before executing the include statement. $result = include($script_name) will work fine and the decision about which script to include can be made at run time.

The way you describe the problem does not seem to indicate that you want to "launch" another process, but I could be wrong.

Upvotes: 2

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