stty: working on stdin vs. ctty

[egmontkob]

stty's manual page says

--file [...] open and use the specified DEVICE instead of stdin

The "instead of stdin" part is not true: by default it doesn't work on stdin, it works on the controlling terminal.

Therefore redirection like stty ... < /dev/pts/N, which works with GNU Coreutils stty, doesn't work here.

Of course, --file is available as a substitute. Nevertheless, unless there's a reason I can't see, I recommend to modify the behavior to match the manual (and not the other way around), that way redirection with < would also work for those who got used to this behavior.

(version 0.2.2 as shipped by Ubuntu 25.10)

[naoNao89]

I tested on GNU stty 9.4

$ podman run --rm ubuntu:latest bash -c stty 2>&1
stty: 'standard input': Inappropriate ioctl for device
Exit code: 1

Redirect from /dev/null

$ podman run --rm ubuntu:latest bash -c "stty < /dev/null 2>&1"
stty: 'standard input': Inappropriate ioctl for device
Exit code: 1

GNU stty does work correctly when stdin IS a TTY

$ podman run --rm -it ubuntu:latest stty
speed 38400 baud; line = 0;
-brkint -imaxbel
Exit code: 0

GNU stty works correctly: Fails when stdin is not a TTY, succeeds when it is.
Root cause: code opens /dev/tty instead of checking stdin first.

coreutils/src/uu/stty/src/stty.rs

Lines 199 to 210 in 1428bd7

	// default to /dev/tty, if that does not exist then default to stdout
	None => {
	if let Ok(f) = std::fs::OpenOptions::new()
	.read(true)
	.custom_flags(O_NONBLOCK)
	.open("/dev/tty")
	{
	Device::File(f)
	} else {
	Device::Stdout(stdout())
	}
	}

[matthiasblaesing]

After an Ubuntu update (25.10 switching from gnu coreutils to uutils) I noticed, that this issue breaks the terminal embedded into NetBeans IDE. The IDE can't set the terminal dimensions anymore resulting in broken rendering. The fix was to remove the rust version and reinstall the gnu version again.

The IDE issues this on each resize (of course with different values):

/bin/stty cols 244 rows 11 < /dev/pts/1 2>/dev/null

This worked and from my reading of the https://pubs.opengroup.org/onlinepubs/9799919799/:

The stty utility shall set or report on terminal I/O characteristics for the device that is its standard input.

it indeed should work. Switching to the version that supplies the target terminal via the -F or --file parameter sounds nice, but is not if you try to work cross platform. I checked a Solaris installation and that would break as their variant of stty does not accept that parameter.

Edit:

Visual result can be seen in NetBeans issue: apache/netbeans#8938. There is also a workaround step documented.

[egmontkob]

This worked and from my reading of the https://pubs.opengroup.org/onlinepubs/9799919799/:

Thanks for looking up the standards! More specifically the frame's URL is https://pubs.opengroup.org/onlinepubs/9799919799/utilities/stty.html

[ChrisDryden]

This issue was also brought up in this sim along with a proposed fix #8608 (comment) once that proposed solution is merged this issue can be resolved

[ChrisDryden]

This should be fully fixed now that #9881 is merged