Public bug reported:
**Title:** uutils stty 0.10.0 ignores cs7 setting on serial ports –
always sets CS8
**System:**
- Kubuntu 26.04 LTS
- Kernel: 7.0.0-42-generic
- Architecture: x86_64
- uutils coreutils: 0.10.0
- GNU coreutils: 9.7
- Serial controller: ASIX AX99100 (PCI ID 125b:9100)
**Problem:**
The uutils implementation of `stty` does not correctly apply the `cs7`
setting.
Command:
`sudo stty -F /dev/ttyS4 9600 cs7 parenb -parodd -cstopb`
Afterwards, `stty -F /dev/ttyS4 -a` still reports:
`-parenb -parodd -cmspar cs8 ...`
Strace confirms that the ioctl TCSETSW2 sends CS8 instead of CS7:
`c_cflag=B9600|CS8|CREAD|PARENB|HUPCL|CLOCAL`
**Comparison:**
Using GNU coreutils stty 9.7:
`sudo gnustty -F /dev/ttyS4 9600 cs7 parenb -parodd -cstopb`
correctly sets:
`parenb -parodd -cmspar cs7 ...`
The setting is then correctly reported by `gnustty -F /dev/ttyS4 -a`.
**Impact:**
This breaks serial communication with industrial CNC equipment requiring
7 data bits, even parity, one stop bit (7E1).
The original transfer script worked under Kubuntu 24.04 with GNU stty.
After upgrading to Kubuntu 26.04, the serial transfer failed with
communication error SR946.
Replacing uutils stty with GNU stty immediately fixed the problem.
**Expected behaviour:**
The uutils implementation should apply `cs7` correctly, matching GNU
coreutils behaviour.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: rust-coreutils 0.10.0-1ubuntu2~26.04.1
ProcVersionSignature: Ubuntu 7.0.0-43.43-generic 7.0.14
Uname: Linux 7.0.0-43-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Fri Nov 6 10:05:12 2026
InstallationDate: Installed on 2018-12-22 (2876 days ago)
InstallationMedia: Kubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
SourcePackage: rust-coreutils
UpgradeStatus: Upgraded to resolute on 2026-10-05 (32 days ago)
** Affects: rust-coreutils (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2173519
Title:
uutils stty ignores cs7 setting on serial ports – always sets CS8
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