stty.py

A Python library for manipulating terminal settings in the style of POSIX stty(1).

Overview

stty provides a high-level, Pythonic interface to terminal I/O settings, including control characters, baud rates, and window size, using the termios and related modules. It allows you to get, set, save, and restore terminal attributes, and to apply them to file descriptors or pseudo-terminals.

Features

• Read and modify terminal attributes (iflag, oflag, cflag, lflag, control characters, speeds, window size)
• Save and load settings to/from JSON files
• Apply settings to file descriptors or pseudo-terminals
• Symbolic and string-based access to all settings
• Emulates many stty(1) features and modes (e.g., raw, evenp, oddp, nl, ek)
• Cross-platform support (where termios is available)

Requirements and Installation

Python 3.13 or above is required. To install this package, run:

pip install stty

Alternatively, since this library does not have any dependencies outside of the Python standard library, simply place stty.py in your project.

Examples

1. Reading and Printing Terminal Settings

from stty import Stty

# Open terminal and get current settings from stdin (fd=0)
tty = Stty(fd=0)
print(tty)  # Print all settings in a compact form

2. Setting Individual Attributes

from stty import Stty

tty = Stty(fd=0)

# Turn off echo
tty.echo = False

# Set erase character to Ctrl-H
tty.erase = "^H"

# Set input baud rate to 9600
tty.ispeed = 9600

# Set number of rows in the terminal window (if supported)
tty.rows = 40

3. Setting Multiple Attributes at Once

from stty import Stty

tty = Stty(fd=0)

# Set several attributes in one call
tty.set(
    echo=False,
    icanon=False,
    erase="^H",
    ispeed=19200,
    ospeed=19200,
    rows=30,
    cols=100
)

4. Saving and Loading Settings

from stty import Stty

tty = Stty(fd=0)

# Save current settings to a file
tty.save("my_tty_settings.json")

# Later, restore settings from the file
tty2 = Stty(path="my_tty_settings.json")
tty2.tofd(0)  # Apply to stdin

5. Using Raw Mode

from stty import Stty

tty = Stty(fd=0)
tty.raw()         # Set raw mode
tty.tofd(0)       # Apply to stdin

6. Working with Pseudo-terminals

from stty import Stty

tty = Stty(fd=0)
m, s, sname = tty.openpty()  # Open a new pty pair and apply settings to slave
print(f"Master fd: {m}, Slave fd: {s}, Slave name: {sname}")

7. Setting Control Characters

from stty import Stty

tty = Stty(fd=0)

# Set interrupt character to Ctrl-C
tty.intr = "^C"

# Set end-of-file character to Ctrl-D
tty.eof = "^D"

# Set suspend character to DEL
tty.susp = "^?"

8. Querying Settings as a Dictionary

from stty import Stty

tty = Stty(fd=0)
settings = tty.get()
print(settings["echo"])   # True or False
print(settings["erase"])  # e.g., '^H'

9. Using Symbolic Constants

from stty import Stty, cs8, tab0

tty = Stty(fd=0)

# Set character size to 8 bits using symbolic constant
tty.csize = cs8

# Set tab delay to tab0
tty.tabdly = tab0

10. Fork new process with pseudo-terminal

x = stty.Stty(0)
x.intr = "^p"
pid, m, sname  = x.forkpty()

if pid == 0: # Child process
    with open("out", "w") as f:
        f.write(str(stty.Stty(0)))
else: # Parent process
    print(sname)
    print("")
    s = os.open(sname, os.O_RDWR)
    print("Parent:", stty.Stty(s))
    os.close(s)

11. Check equality of (all termios and winsize attributes of) 2 Stty objects

x = stty.Stty(0)
y = stty.Stty(0)

if x.get() == y.get():
    print("equal")
else:
    print("not equal")

12. Check equality of (some termios and winsize attributes of) 2 Stty objects

x = stty.Stty(0)

if x.eq(echo=True, eof="^D")
    print("echo is True and eof is ^D")
else:
    print("echo is False or eof is not ^D")

API Reference

Classes

Stty

Manipulate terminal settings in the style of stty(1).

Constructor:

Stty(fd: int = None, path: str = None, **opts)

• fd: File descriptor to read settings from.
• path: Path to JSON file to load settings from.
• **opts: Any supported terminal attribute as a keyword argument.

Methods:

• get() -> dict Return dictionary of termios and winsize attributes available on the system mapped to their respective values.

• set(**opts) Set multiple attributes as named arguments.

• eq(**opts) Return True if all attributes, which are specified as named arguments, have values equal to those of the corresponding named arguments; return False otherwise.

• save(path: str = None) Return deep copy of self or save JSON. This mimics "stty -g".

• load(path: str) Load termios and winsize from JSON file.

• fromfd(fd: int) Get settings from terminal.

• tofd(fd: int, when=TCSANOW, apply_termios=True, apply_winsize=True) Apply settings to terminal.

• evenp(plus=True) Set/unset evenp combination mode.

• oddp(plus=True) Set/unset oddp combination mode.

• raw() Set raw combination mode.

• nl(plus=True) Set/unset nl combination mode.

• ek() Set ek combination mode.

• openpty(apply_termios=True, apply_winsize=True) Open a new pty pair and apply settings to slave end.

• forkpty(apply_termios=True, apply_winsize=True) Call os.forkpty() and apply settings to slave end.

Attribute Access:

• All terminal attributes (e.g., echo, icanon, erase, ispeed, rows, etc.) are accessible as properties.
• Setting an attribute updates the internal state and validates the value.

Constants

• TCSANOW, TCSADRAIN, TCSAFLUSH: the values accepted by the when named argument of Stty.tofd(). Compare with termios.tcsetattr().
• Symbolic constants for masks and values (e.g., cs8, tab0, etc.) are available as module attributes.

Data

• settings: A dictionary describing all available Stty attributes and their possible values on the current platform.

Functions

• settings_help_str: Return help string about all available Stty attributes and their possible values on the current platform.
• settings_help: Print help message about all available Stty attributes and their possible values on the current platform.

Compatibility

• Requires Python 3.x and a POSIX-like system with the termios module.
• Some features depend on platform support (e.g., window size).

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

Author

Soumendra Ganguly, 2025

See Also

• stty(1) manpage
• Python termios documentation