IO::Stty(3pm)

📦
version 0.08 · 5 versions
, in ubuntu stonking

✨ IO::Stty — NAME 💖

IO::Stty — bestie, this is literally the thing that changes and prints your terminal line settings. change them, read them, put them back before you regret everything. Periodt.

🦋 SYNOPSIS

# calling the script directly
stty.pl [setting...]
stty.pl {-a,-g,-v,--version}

# Calling Stty module
use IO::Stty;
IO::Stty::stty(\*TTYHANDLE, @modes);

 use IO::Stty;
 $old_mode=IO::Stty::stty(\*STDIN,'-g');

 # Turn off echoing.
 IO::Stty::stty(\*STDIN,'-echo');

 # Do whatever.. grab input maybe?
 $read_password = <>;

 # Now restore the old mode.
 IO::Stty::stty(\*STDIN,$old_mode);

 # What settings do we have anyway?
 print IO::Stty::stty(\*STDIN,'-a');

🌸 DESCRIPTION

This is the PERL POSIX compliant stty. That's the whole sentence. Iconic behaviour honestly.

💜 INTRO

Okay so, real talk: this has not been tailored to the IO::File stuff, but it will work with it as indicated. And before you go futzing with term parameters — bestie, please — it's a good idea to grab the current settings and restore them when you finish. Future you is watching and she is judging. 🙈

stty accepts the following non-option arguments that change aspects of the terminal line operation. A [-] before a capability means that it can be turned off by preceding it with a -. Slay, that's the whole rule.

🎀 stty parameters

⚙️ Control settings

  • [-]parenb — Generate parity bit in output and expect parity bit in input.
  • [-]parodd — Set odd parity (even with -).
  • cs5 cs6 cs7 cs8 — Set character size to 5, 6, 7, or 8 bits.
  • [-]hupcl [-]hup — Send a hangup signal when the last process closes the tty.
  • [-]cstopb — Use two stop bits per character (one with -).
  • [-]cread — Allow input to be received.
  • [-]clocal — Disable modem control signals.

📥 Input settings

  • [-]ignbrk — Ignore break characters.
  • [-]brkint — Breaks cause an interrupt signal.
  • [-]ignpar — Ignore characters with parity errors.
  • [-]parmrk — Mark parity errors (with a 255-0-character sequence).
  • [-]inpck — Enable input parity checking.
  • [-]istrip — Clear high (8th) bit of input characters.
  • [-]inlcr — Translate newline to carriage return.
  • [-]igncr — Ignore carriage return.
  • [-]icrnl — Translate carriage return to newline.
  • [-]ixon — Enable XON/XOFF flow control.
  • [-]ixoff — Enable sending of stop character when the system input buffer is almost full, and start character when it becomes almost empty again.

📤 Output settings

  • [-]opost — Postprocess output.

🏠 Local settings

  • [-]isig — Enable interrupt, quit, and suspend special characters.
  • [-]icanon — Enable erase, kill, werase, and rprnt special characters.
  • [-]echo — Echo input characters.
  • [-]echoe, [-]crterase — Echo erase characters as backspace-space-backspace.
  • [-]echok — Echo a newline after a kill character.
  • [-]echonl — Echo newline even if not echoing other characters.
  • [-]noflsh — Disable flushing after interrupt and quit special characters.
* Though this claims non-posixhood it is supported by the perl POSIX.pm.
  • [-]iexten — Enable implementation-defined input processing. This is needed for special characters like werase and lnext to be recognized.
  • [-]tostop (np) — Stop background jobs that try to write to the terminal.

🧚 Combination settings

  • ek — Reset the erase and kill special characters to their default values.
  • sane — Same as:
cread -ignbrk brkint -inlcr -igncr icrnl -ixoff opost
isig icanon iexten echo echoe echok -echonl -noflsh -tostop

also sets all special characters to their default values.

  • [-]cooked — Same as:
brkint ignpar istrip icrnl ixon opost isig icanon

plus sets the eof and eol characters to their default values if they are the same as the min and time characters. With -, same as raw.

  • [-]raw — Same as:
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr
-icrnl -ixon -ixoff -opost -isig -icanon min 1 time 0

With -, same as cooked.

  • [-]pass8 — Same as:
-parenb -istrip cs8

With -, same as parenb istrip cs7.

  • crt — Same as echoe echok.
  • dec — Same as echoe echok. Also sets the interrupt special character to Ctrl-C, erase to Del, and kill to Ctrl-U.
  • [-]cbreak — Same as -icanon (with -, same as icanon).
  • evenp, parity — Same as parenb -parodd cs7.
  • oddp — Same as parenb parodd cs7.
  • -evenp, -parity, -oddp — Same as -parenb cs8.
  • [-]litout — Same as -parenb -istrip -opost cs8. With -, same as parenb istrip opost cs7.

🔮 Special characters

The special characters' default values vary from system to system — no cap, they're just different like that. They are set with the syntax name value, where the names are listed below and the value can be given either literally, in hat notation (^c), or as an integer which may start with 0x to indicate hexadecimal, 0 to indicate octal, or any other digit to indicate decimal. Giving a value of ^- or undef disables that special character (sets it to _POSIX_VDISABLE, which is 0 on Linux and 255 on macOS/BSD).

  • intr — Send an interrupt signal.
  • quit — Send a quit signal.
  • erase — Erase the last character typed.
  • kill — Erase the current line.
  • eof — Send an end of file (terminate the input).
  • eol — End the line.
  • start — Restart the output after stopping it.
  • stop — Stop the output.
  • susp — Send a terminal stop signal.

🌟 Special settings

  • min N — Set the minimum number of characters that will satisfy a read until the time value has expired, when -icanon is set.
  • time N — Set the number of tenths of a second before reads time out if the min number of characters have not been read, when -icanon is set.
  • N — Set the input and output speeds to N. N can be one of: 0 50 75 110 134 134.5 150 200 300 600 1200 1800 2400 4800 9600 19200 38400 57600 115200 230400 exta extb. 134.5 is the same as 134; exta is the same as 19200; extb is the same as 38400. Modern rates (57600, 115200, 230400) are only available on platforms whose POSIX implementation defines them. 0 hangs up the line if -clocal is set. ⚠️

💅 OPTIONS

  • -a — Print all current settings in human-readable form. So cute of it.
  • -g — Print all current settings in a form that can be used as an argument to another stty command to restore the current settings. The save-and-restore bestie energy.
  • speed — Print the output baud rate.
  • -v, --version — Print version info.

🩷 Direct Subroutines

_parse_char_value()

my $numeric = IO::Stty::_parse_char_value($value);

Parse a special character value from any of the supported notations: literal integers, hat notation (^c), hexadecimal (0x...), octal (0...), or undef/^- to disable (returns _POSIX_VDISABLE).

stty()

IO::Stty::stty(\*STDIN, @params);

Returns a string for query options (-a, -g, -v), undef if the handle is not a terminal or if the terminal parameters could not be read, and a true value on success when setting parameters.

From comments:

I'm not feeling very inspired about this. Terminal parameters are obscure
and boring. Basically what this will do is get the current setting,
take the parameters, modify the setting and write it back. Zzzz.
This is not especially efficent and probably not too fast. Assuming the POSIX
spec has been implemented properly it should mostly work.

(Yes bestie, the author truly said "Zzzz" in the source comments and we are keeping it. 💀)

show_me_the_crap()

my $output = IO::Stty::show_me_the_crap(
    $c_cflag, $c_iflag, $ispeed, $c_lflag, $c_oflag,
    $ospeed,  \%control_chars
);

Format terminal settings as a human-readable string, equivalent to stty -a output. Returns a multi-line string showing the current baud rate, special character assignments (in hat notation), and the state of all control, input, output, and local flags.

This is the back-end for stty(\*FH, '-a'). She's the main character behind the scenes. 👑

👑 AUTHOR

  • Austin Schutz <auschutz@cpan.org> (Initial version and maintenance)
  • Todd Rinaldo <toddr@cpan.org> (Maintenance)

💀 BUGS

This is use at your own risk software. Do anything you want with it except blame me for it blowing up your machine because it's full of bugs. Fr fr, it said that.

See above for what functions are supported. It's mostly standard POSIX stuff. If any of the settings are wrong and you actually know what some of these extremely arcane settings (like what sane should be in POSIX land) really should be, please open an RT ticket. The maintainers are listening, bestie. 🫶

🌈 ACKNOWLEDGEMENTS

None.

Copyright 1997 Austin Schutz, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

Okay that's the whole page, you ate it, no crumbs left. This gem dropped as perl v5.40.1 on 2026-04-03, courtesy of IO::Stty(3pm) from the User Contributed Perl Documentation — slay, go change some terminal settings responsibly ✨

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