$ Linux Command

System

stty

Change and report terminal line settings.

terminalttysettingsserialconfiguration

Additional Notes

stty displays and modifies the parameters of a terminal device. It controls the terminal driver's behavior, including baud rate, character size, flow control, line discipline, and how special characters (like erase, kill, interrupt) are interpreted.

This command is essential for configuring serial ports, fixing terminal display issues, and setting up embedded device connections. Without arguments, stty shows the current terminal settings in a human-readable format. The -a flag shows all settings.

Syntax

stty [options] [setting...]

Parameters

  • -F device: Specify the terminal device (e.g., /dev/ttyUSB0, /dev/ttyS0).
  • setting: Configuration changes in the form keyword value or keyword.

Common Options

  • -a, --all: Show all current settings in human-readable form.
  • -g, --save: Show settings in a stty-readable format (for saving and restoring).
  • -F, --file device: Open and operate on the specified device instead of stdin.

Common Settings

Speed:

  • speed N: Set baud rate (e.g., 9600, 115200).
  • ispeed N: Set input baud rate.
  • ospeed N: Set output baud rate.

Character Size and Parity:

  • cs5, cs6, cs7, cs8: Set character size to 5, 6, 7, or 8 bits.
  • parity: Enable parity generation and checking.
  • -parity: Disable parity.
  • parodd: Set odd parity (default even).
  • cmspar: Use stick parity.

Flow Control:

  • ixon: Enable XON/XOFF flow control (Ctrl-S/Ctrl-Q).
  • -ixon: Disable XON/XOFF flow control.
  • ixoff: Enable sending of XON/XOFF characters.
  • crtscts: Enable hardware (RTS/CTS) flow control.
  • -crtscts: Disable hardware flow control.

Stop Bits:

  • cstopb: Two stop bits.
  • -cstopb: One stop bit.

Input Processing:

  • ignbrk: Ignore break signals.
  • brkint: Make break signal generate an interrupt.
  • icrnl: Map carriage return to newline on input.
  • opost: Enable output processing.
  • onlcr: Map newline to carriage return-newline on output.

Local Settings:

  • echo: Echo input characters back to output.
  • -echo: Disable echo (for password prompts).
  • echoe: Echo erase character as backspace-space-backspace.
  • echok: Echo newline after kill character.
  • icanon: Enable canonical mode (line-by-line input with editing).
  • -icanon: Enable raw mode (character-by-character input).
  • isig: Enable signal character processing (Ctrl-C, Ctrl-Z).
  • -isig: Disable signal character processing.

Special Characters:

  • intr CHAR: Set interrupt character (default Ctrl-C).
  • quit CHAR: Set quit character (default Ctrl-\).
  • erase CHAR: Set erase character (default Backspace or Del).
  • kill CHAR: Set kill character (default Ctrl-U).
  • eof CHAR: Set EOF character (default Ctrl-D).
  • susp CHAR: Set suspend character (default Ctrl-Z).

Examples

stty -a

Show all current terminal settings.

stty -F /dev/ttyUSB0 115200 cs8 -cstopb -parity

Configure a serial port at 115200 baud, 8 data bits, 1 stop bit, no parity.

stty -g

Show settings in a format that can be saved and restored.

stty -echo

Disable echo (useful for password entry scripts).

stty echo

Re-enable echo.

stty raw

Set the terminal to raw mode (no line buffering, no signal processing).

stty sane

Reset the terminal to a reasonable default state (useful after a program crashes with garbled terminal).

stty intr '^C'

Set the interrupt character to Ctrl-C.

stty erase '^?'

Set the erase character to Delete.

Practical Notes

  • If your terminal becomes garbled, stty sane usually restores normal behavior.
  • stty raw is used by programs like ssh and telnet for direct character transmission.
  • Serial port configuration (stty -F /dev/ttyUSB0) requires appropriate permissions.
  • Save and restore settings with OLD=$(stty -g) and stty "$OLD".
  • The sane setting is a safe default that works for most modern terminals.
  • Changes affect only the terminal device associated with the current process (unless -F is used).