Terminal

tty (teletype)

• It connects the shell to the operating system
• It's part of the Linux Kernel

• The tty itself doesn’t display anything. It’s just the interface the kernel exposes for text I/O.

• /dev/tty1: virtual console in Linux (Ctrl+Alt+F1-F6)

• /dev/ttyS0: serial port
• /dev/pts/0: pseudo-terminal used by a terminal emulator

# Access tty from another terminal
echo "Hello TTY1" > /dev/tty1
cat < /dev/tty1

Terminal emulator

• A program you run in user-space that provides a window (GUI) to interact with a shell.

• It creates a pseudo-terminal (pty) to talk to the kernel's tty interface.

• Alacritty

• WezTerm
• Ghostty
• Kitty
• xterm

Workflow

-> [Keyboard] -> [Terminal Emulator GUI] -> [Pseudo-terminal (pty)] -> [Kernel tty subsystem] <> [Shell] <- [Kernel tty subsystem] <- [Pseudo-terminal] <- [Terminal Emulator GUI] <- [Screen]