Things to learn about Linux

I asked on Twitter today what Linux things they would like to know more about. I thought the replies were really cool so here’s a list (many of them could be discussed on any Unixy OS, some of them are Linux-specific)

• tcp/ip & networking stuff
• what is a port/socket?
• seccomp
• systemd
• IPC (interprocess communication, pipes)
• permissions, setuid, sticky bits, how does chown work
• how the shell uses fork & exec
• how can I make my computer a router?
• process groups, session leaders, shell job control
• memory allocation, how do heaps work, what does malloc do?
• ttys, how do terminals work
• process scheduling
• drivers
• what’s the difference between Linux and Unix
• the kernel
• modern X servers
• how does X11 work?
• Linux’s zero-copy API (sendfile, splice, tee)
• what is dmesg even doing
• how kernel modules work
• embedded stuff: realtime, GPIO, etc
• btrfs
• QEMU/KVM
• shell redirection
• chroot
• filesystems & inodes
• what is RSS, how do I know how much memory my process is using
• iptables
• what is a network interface exactly?
• what is syslog and how does it work?
• how are logs usually organized?
• virtual memory
• bootloader, initrd, kernel parameters
• the ip command
• what are all the files that are not file files (/dev, stdin, /proc, /sys)
• sed and awk
• namespaces, cgroups, docker, SELinux, AppArmor
• debuggers
• what’s the difference between threads and processes?
• if unix is text-based, how do desktop environments like GNOME fit in?
• how does the “man” system work.
• kpatch, kgraph, kexec
• more about the stack. Are C vars really stack slots? How tf do setjmp and longjmp work?
• package management
• mounts and vfs

this is great for so many reasons!

1. I need to draw 11 more drawings about Linux this month and these are such great ideas
2. there are many things I don’t know on this list and it’s a cool reminder of how much interesting stuff there still is to learn! A few of these I barely even know what they are (dbus, SELinux) or only have a pretty sketchy notion (seccomp, how X11 works, many more)
3. it’s also a cool reminder of how far I’ve come – I at least know where to start with most of the things on this list, even if I definitely could not explain a lot of them in detail without looking some stuff up.

Also I sometimes want to remind people that you too could write interesting blog posts / drawings on the internet – for instance “what is dmesg even doing” is an interesting topic, and totally possible to learn about! (I just read dmesg on Wikipedia and now I know more!)