Missing Semester 10 - Potpourri

Miscellaneous programming topics and tools: keyboard remapping, daemons, virtual machines and more 💪

Written by Eva Dee on (about a 4 minute read).

Keyboard remapping

This usually involves some software that is listening and, whenever a certain key is pressed, it intercepts that event and replaces it with another event corresponding to a different key.

Further links for Karabiner (macOS) config:

👍 It's recommended to use goku (and the .edn format) for the Karabiner config file instead of .json format, which is super bloated.

My current remappings:

  • CapsLock -> another modifiter key
  • Shift + CapsLock -> Caps Lock
  • Right Shift + w/a/s/d -> right-side arrow keys
  • CapsLock + f -> full-screen everything
  • CapsLock + t -> open terminal

Daemons

Daemons are processes that are often started when the system is bootstrapped and terminate only when the system is shut down. Because they don’t have a controlling terminal, they run in the background. The programs that run as daemons often end with a d to indicate so.

For example, sshd, the SSH daemon, is the program responsible for listening to incoming SSH requests and checking that the remote user has the necessary credentials to log in.

🤔 What is the difference between daemons and launch agents?

Daemons are system-wide services that always run in the background, while agents describe regular services that are to be executed on user-specific events.

🤔 Where can I find launch daemons and agents?

  • ~/Library/LaunchAgents
  • /Library/LaunchAgents
  • /Library/LaunchDaemons
  • /System/Library/LaunchAgents
  • /System/Library/LaunchDaemons

FUSE

Filesystem in Userspace (FUSE) is a software interface for Unix and Unix-like computer operating systems that lets non-privileged users create their own file systems without editing kernel code. This is achieved by running file system code in user space while the FUSE module provides only a "bridge" to the actual kernel interfaces.

FUSE is useful especially for writing Virtual file systems where you don't store/retrieve data from an actual disk.

Examples:

  • GmailFS: filesystem which stores data as mail in Gmail
  • WikipediaFS: View and edit Wikipedia articles as if they were real files

Backups

More info on backups here.

APIs

👍

Command-line Arguments

  • --help flag to display brief usage instructions for the tool.
  • --dry-run which only prints what the command would do but does not actually perform the change.
  • -i for “interactive” (especially for destructive actions)
  • --version or -V for program version.
  • --verbose or -v flag to produce more verbose output. -vvv for even more verbose output
  • --quiet flag for making it only print something on error.
  • - in place of a file name means “standard input” or “standard output”, depending on the argument.
  • -r for recursive
  • -- makes a program stop processing flags and options (things starting with -) in what follows, letting you pass things that look like flags without them being interpreted as such: rm -- -r or ssh machine --for-ssh -- foo --for-foo.

Window managers

Rectangle (similar to RIP Spectacle) vs Magnet vs others

VPNs

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Markdown

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Hammerspoon (desktop automation on macOS)

Hammerspoon is a desktop automation framework for macOS. It lets you write Lua scripts that hook into operating system functionality, allowing you to interact with the keyboard/mouse, windows, displays, filesystem, and much more.

Booting + Live USBs

Live USBs are USB flash drives containing an operating system.

Docker, Vagrant, VMs

Virtual machines and similar tools like containers, let you emulate a whole computer system, including the operating system.

Vagrant is a tool that lets you describe machine configurations (operating system, services, packages, etc.) in code, and then instantiate VMs with a simple vagrant up. Docker is conceptually similar but it uses containers instead.

Notebook programming

Like Jupyter, for Python.

GitHub

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