Linux

It sources (includes) any file found in ~/.bashrc.d/ so check that directory.

Check /etc/skel/.bashrc, if it's in there as well, it was set up by your distro.

What it does is check for the existence of ~/.bashrc.d and, if it finds one, sources all the files inside it. This effectively means that you can create script files like ~/.bashrc.d/myfile.sh and they will have the same effect as if they had been put directly into .bashrc. Some people prefer having one file for each "bashrc thing" whilst some prefer just having one big file. Ultimately it's personal preference.

Ugh, I hate ChatGPT. If this is Bash (which it is, because it's literally looking for files in a directory called ~/.bashrc.d), then it should god damned well be using syntax and language features that we've had for at least twenty fucking years. Specifically, if you're writing for Bash (and not POSIX shell), you better be using [[ ]] rather than [ ]. This wiki is my holy book I use to keep the demons away when writing Bash, and it does a simply fantastic job of explaining why you should use God damned double square brackets.

ChatGPT writes shitty, horrible, buggy ass Bash. This is relatively decent for ChatGPT (it even makes sure the files are real files and not symlinks), but I've had to fix enough terrible fucking shitty AI Bash to have no tolerance for even the smallest misstep from it.

Sincerely, A senior developer who is known as the Bash wizard at work.

EDIT: Sorry, OP. ChatGPT did not, in fact, write this code, and I am going to leave my comment here as a testament to what a big smelly dick I was here.

Looks like this is in the standard Fedora /etc/skel/.bashrc.

It first checks if ~/.bashrc.d is an existing directory. If this it the case it then iterates over all entries in that directory. In this iteration it checks if the entry is a file and if this is the case it sources that file using the bash-internal shorthand . for source.

So it basically executes all scripts in ~/.bashrc.d. This makes it possible for you to split your bash configuration into multiple files. This quite common and a lot of programs already support it (100% depends on the program, though).

This is absolutely harmless as it is. But: if you or a program places anything in the directory ~/.bashrc.d it WILL be sourced everytime you start a bash.

A slightly better variant would be iterating over ~/.bashrc.d/*.sh instead of just ~/.bashrc.d/* to make sure to only grab files with the .sh suffix (even if suffixes are basically meaningless from a technical point of view) and also test for the file being executable (-x instead of -f).

This would make sure that only files that are ending with .sh and that are executable are sourced. The “attack vector”, if you want to call it like that, would then be a bit more narrow than just placing a file in a directory.

As for why it’s there: Did you ever touch your .bashrc? If not, maybe it is there since the beginning because it’s in the so-called skeleton (see /etc/skel/.bashrc) that was used to initialize certain files on user account creation.

Definitely non-standard, but I have something almost identical that I very consciously added and really simplifies a lot of things.

I couldn’t say how it got there, but it’s a standard & common Unix pattern and unlikely to be malicious. It will have no effect if the ~/.bashrc.d directory doesn’t exist. If it does exist, then each file in the directory will be sourced.

seems similar to the set up for systemd snippets, where you can avoid changing default config files for systemd units and instead use a drop in file in that created .d dir to load and overwrite the defaults on boot for whatever specific thing. don't know anything that uses this for bashrc, tho. most likely harmless, especially if there's no created bashrc.d yet.