a program’s input and outputs are streams of bytes

everything you type goes into standard input (almost)

Illustration of a program, represented by a big box with a smiley face. There is an “in” arrow going into it, and “1 out” and “2 ERR” arrows coming out of it.

all the output you see comes from either standard output or standard error

your terminal emulator can only communicate with programs by reading/writing bytes

some inputs/outputs are text and some are special instructions

in: mouse position, ctrl+left arrow
out: make text green, make cursor invisible

these special instructions are called “escape codes”

they’re called “escape codes” because they all start with the ESC character

five ways people print out ESC: - \033 - ^[ - ESC - \e - \x1b

example: how colours get set

program: “^[[31m”

Terminal emulator, represented by a box wth little arms and legs and a cute cursor winking face: “ok, I’ll make text red from now on!!”

(there are also codes for bold, underline, background colour)

programs can easily “break” your terminal by printing escape codes

program, represented by a frowning rectangle: “oops I made your cursor disappear”

It’s easy to fix though, run reset to print a special escape code that resets everything