Jacfger / Janksh

Janksh

As the name suggest, it's a very janky shell program, with no guarantee about memory leak protection, and functionality (??).

This was a coursework about building a simple shell program. But I was kinda proud of what I ended up building. Not the prettiest code ngl but nonetheless I had enjoyed building it.

This repo is to document part of my journey on learning Linux system programming; not really intended for others to use. But if you have any comment on my coding style or my stupid mistakes, feel free to open an issue or PR. I'm always open to learn. (Or you can just laugh and let it go, that's fine too :D)

Functionality

While it is very janky, it does have some functions (surprisingly).

• Command parser. Not a very complicated nor functional one, but it does the job. (And it does assume you type the command quite cleanly. Insert spaces to make it pretty!)
• Command execution. It's actually a bit more complicated than one would've imagine. Which I had a lot of fun understanding and playing it. Modern shells are much more complicated, but in this case fork() + exec() did the trick for me.
• ^C Keyboard interruption. Classic.
• Directory navigation. cd command is here, the most important command (imo) in a shell program.
• Background job execution. With a little & at the end, make the command executing at background while allowing user to typing other commands. fg, bg, ^Z are all here as well.
• Job monitoring. Primarily emulating the jobs command in bash shell.
• exit command. Exits the shell program so you don't kill command isn't needed. Ctrl+D doesn't work for some reason, I had encountered quite some problems detecting ^D (EOF) which sometimes can be mixed up with other character irrc. I hate this limitation but it is what it is for such janky shell. Damn ignoreeof. It seems like the current implementation to grap lines into buffer isn't the best way to do it. But the deadline is near so
• etc. Tired of listing. :D

I don't know what title to put here but it's kind of a summary

This project is coursework about a shell program where functionality is the least of its concern. Because its extreme simplicity and jankiness, I believe this actually serves as a perfect project and example for rookies like me to understand some very entry level processes management of Linux, or Unix system in general even.