grant horwood

php developers generally don’t put a lot of thought into reading files from disk. we usually just call file or file_get_contents or similar, shovel the whole thing into ram, and then fight with the resulting array or string. if we want to do simple things with small files, it works okay. but php can do a lot more.

in this article, we’re going to look at php’s file pointer and how to manipulate it using commands like fseek and ftell, and by the end we’ll be able to build a pure php version of linux’s tail -f command.

in this series, we’ve been looking at how to write command line applications in php using macrame. in the previous installment, we covered the basic structure of macrame scripts, getting user input both as text and from interactive menus, parsing command-line arguments, and styling our output text.

the sample application we’re building is a script that fetches a list of a mastodon user’s followers and outputs the data in a nicely-formatted table. it looks like this:

i recently worked on a rescue project where the original dev wanted to sort an array of item objects first by manufacturer name and then by price, descending. their ‘solution’ was an eighty-line foreach mess of fiddling with array keys. it was difficult to read, more difficult to modify, and didn’t even work correctly lots of the time. i replaced the whole thing with a five-line usort call.

usort stands for ‘user-defined sort’. it allows us, as devs, to write our own sorting rules (plural!) and makes working with arrays of complex data easier.

in this post, we’re going to take a thorough look at sorting arrays with usort. we’ll go over the basics of how the function works, write some ascending and descending sorts on integers and strings, and then cover how to sort on multiple values.

php isn’t the sort of language where developers usually think about things like memory. we just sort of sling around variables and functions and let the internals figure out all that ‘ram stuff’ for us. let’s change that.

in first part of this series, we built a php script that was able to run a number of tasks concurrently by forking child processes. it worked pretty well, but there was a glaring, unaddressed problem: there was no way for those child processes to send data back to the parent process.

in this installment, we’re going to solve that issue by using shmop, php’s “shared memory operations”.

i often joke that php is a systems programming language that you can also use to create a home page. it’s not really true, of course; no one is going to write, say, a video driver in php. but it does highlight the fact that php has an absolute tonne of functionality that is either straight through calls to c or built-in libraries that allow us to access all sorts of operating systems features.

in this series, we’re going to leverage some of that power to write a php program that does multiple things at the same time. we’ll do that by using pcntl_fork to create a number of child processes that run simultaneously. then in part two, we’ll be looking at shmop, php’s ‘shared memory operations’, as a way to allow those processes to communicate their results.