RC 2022 Day 4 - pipes

2022-08-11

Today I made a bit more progress on my shell! I can now change directory, make other system calls, and run multiple commands (separated by &&).

I started working on implementing pipes (|) and learnt some cool stuff:

• file descriptors are unique IDs for open files in a process. Each process has a table of file descriptors for currently open files and uses those IDs to operate on the files. Shells use file descriptors 0, 1, and 2 for stdin, stdout, and stderr, respectively
• /proc is a virtual file system with a bunch of info about what's happening in the kernal THAT YOU CAN LOOK AT (eg ls /proc)
• ls -l /proc/self/fd prints the file descriptors table in the current process

Today I also got to meet a few more people and had some really interesting chats, paired with Sophia on some environment setup stuff, and attended a really excellent debugging workshop run by Julia.