Linux bash

Common tools:

$cat file_name | wc -l = "word count" command gets flags like (-c,-l,-m,-w) to show you the number of bytes, lines, characters or words, respectively

$? = holds your exited returned value so you can use it later in the script

$$ = means current PID (echo $$)

$! = is the PID of the last program your shell ran in the background (e.g. myprog &)

$tput = is a command which allows you to control the cursor on the terminal and the format of content that is printed

https://ryanstutorials.net/bash-scripting-tutorial/bash-user-interface.php

$man bash, press / and start search bash commands, variables, etc.