afconvert(1) - an audio file format converter, which includes Apple's superior AAC codec from the Core Audio framework

    diskutil(8) - tons of tools for fixed and removable storage

    afconvert in.wav -o out.m4a -q 127 -s 2 -b 160000 -f m4af -d 'aac '

    mb=300; diskutil eraseVolume APFS myramdisk `hdiutil attach -nomount ram://$((mb*2048))`

   hear (macOS speech recognition and dictation via the command line)

(Uses built-in macOS capabilities for transcription from audio to text.)

open -n file.pdf : opens new instance of Preview application which is useful if you want to open the same file twice (for example to look at different pages at once).

caffeinate -d : prevents display turning off, useful if you want to look at display without moving mouse.

Docs are at https://ss64.com/mac/diskutil.html

https://terminaltrove.com/categories/macos/

You might find one you've never heard of that is useful! :)