Andreas
c9c8714651
procps-ng 4.0 rewrote w to skip utmp entirely, leaving TTY blank, IDLE identical for all users, and WHAT pointing at the sshd parent process instead of the user's shell. Reads utmp via who(1), idle via tty atime, and foreground process group via the tpgid field in /proc/pid/stat. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
1.8 KiB
1.8 KiB
w
Drop-in replacement for w(1) on systems with procps-ng 4.x.
Problem
procps-ng 4.0 rewrote w to read from /proc instead of utmp, but
the process→session→tty mapping is broken. On a typical SSH login you get:
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
andreas 192.168.10.11 12:52 2:17 0.00s ? sshd: andreas [priv]
andreas 192.168.10.11 12:52 2:17 0.00s ? sshd: andreas [priv]
Three bugs in one:
| Column | Bug | Root cause |
|---|---|---|
| TTY | blank | utmp never read |
| IDLE | same for everyone | can't stat the tty without knowing its name |
| WHAT | shows sshd: [priv] |
picks the SSH privilege-separation parent instead of the user's shell |
Solution
This script reads the right sources directly:
- utmp via
who -u— correct TTY name, login time, source host /dev/<tty>atime — real idle time/proc/pid/stattpgidfield — kernel's own record of each tty's foreground process group, used for JCPU/PCPU/WHAT (noTIOCGPGRPioctl needed, which would fail on terminals we don't own anyway)
Example output
13:07:07 up 15 min, 3 users, load average: 0.05, 0.10, 0.09
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
andreas pts/0 192.168.10.11 12:52 1:54 0.0s 0.0s -bash
andreas pts/1 192.168.10.11 12:52 0s 37.5s 37.5s claude
stephan pts/2 192.168.10.165 13:02 1s 0.0s 0.0s -bash
Install
cp w ~/bin/w
chmod +x ~/bin/w
Make sure ~/bin appears before /usr/bin in your PATH.
Requirements
Python 3.6+, who, uptime — all standard on any Linux system.
Tested on Ubuntu 24.04 (Noble) with procps-ng 4.0.4.