print-to-terminal

what happens when i print in python, how does it show up in terminal

tags: learning terminal programming

content

• when i do print in python, the python program doesn’t actually print to terminal
• the program sends bytes to stdout, and stdout happens to be a terminal
• and then the terminal decides how to deal with it
  • terminal deals with the incoming bytes based on some protocol, and deals with escape sequence accordingly
    • e.g., if it’s ^[[A, terminal moves cursor up by 1 row
      • ^[ is the start of control sequence

print("hi")
   ↓
Python runtime
   ↓
UTF-8 bytes
   ↓
OS write() syscall
   ↓
stdout file descriptor
   ↓
terminal emulator
   ↓
escape-sequence parser
   ↓
screen update

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• escape-sequence-example

reference