ps doesn't support "thcount" format specifier on Xenial
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
procps (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned | ||
Xenial |
Fix Released
|
Undecided
|
Heitor Alves de Siqueira |
Bug Description
[Impact]
ps -o thcount prints out an error (error: unknown user-defined format specifier "thcount")
[Description]
The Xenial version of procps has a bug in the thcount format specifier. ps doesn't recognize it, and complains about an unknown user-defined format.
This is due to the format specifier table in ps/output.c, which is queried with a binary search. Since the "thcount" entry appears out of order in Xenial, it can't be looked up and the program fails with the "unknown user-defined format specifier" error.
This has been fixed upstream by the commit below:
- Fix for Bug:1174313 (3a52dfa34027)
$ git describe --contains 3a52dfa34027
v3.3.12~58^2
$ rmadison procps
procps | 2:3.3.10-4ubuntu2 | xenial | source, ...
procps | 2:3.3.10-4ubuntu2.4 | xenial-security | source, ...
procps | 2:3.3.10-4ubuntu2.4 | xenial-updates | source, ... <--------
procps | 2:3.3.12-3ubuntu1 | bionic | source, ...
procps | 2:3.3.12-3ubuntu1.1 | bionic-security | source, ...
procps | 2:3.3.12-3ubuntu1.2 | bionic-updates | source, ...
Releases starting with Bionic already have this fix, so it's only needed for Xenial.
[Test case]
1. Boot up a Xenial environment with e.g. an lxd container:
# lxc launch images:
2. Execute ps with the '-o thcount' options:
# lxc exec xenial -- ps -o thcount
error: unknown user-defined format specifier "thcount"
Usage:
ps [options]
Try 'ps --help <simple|
or 'ps --help <s|l|o|t|m|a>'
for additional help text.
For more details see ps(1).
[Regression Potential]
The fix just fixes the order of two entries in the format specifier array, so the regression potential is very low. Furthermore, the patch has been present and tested in up-to-date versions of procps since Bionic. Any new regressions introduced in Xenial will be checked with autopkgtest.
[Original Description]
In Ubuntu 12.04.5 LTS (procps 1:3.2.8-
$ export PS_FORMAT=thcount
$ ps
THCNT
1
1
In Ubuntu 14.04.1 LTS (procps 1:3.3.9-1ubuntu2), it does not work anymore:
$ export PS_FORMAT=thcount
$ ps
warning: $PS_FORMAT ignored. (unknown user-defined format specifier "thcount")
PID TTY TIME CMD
6593 pts/1 00:00:00 ps
16633 pts/1 00:00:00 bash
Other PS_FORMAT specifiers still work fine (I have tried many, but not all).
In real-life usage, a more complex PS_FORMAT would of course be used, such as PS_FORMAT=
Workaround: use nlwp instead of thcount (they are alias to the same data, and nlwp works fine in both versions).
Related branches
- Christian Ehrhardt (community): Approve
- Canonical Server: Pending requested
- git-ubuntu developers: Pending requested
-
Diff: 57 lines (+35/-0)3 files modifieddebian/changelog (+7/-0)
debian/patches/lp1410558-fix-thcount.patch (+27/-0)
debian/patches/series (+1/-0)
tags: | added: sts |
description: | updated |
Changed in procps (Ubuntu): | |
status: | Confirmed → Fix Released |
Changed in procps (Ubuntu Xenial): | |
status: | New → In Progress |
assignee: | nobody → Heitor Alves de Siqueira (halves) |
summary: |
- PS_FORMAT=thcount does not work anymore + ps doesn't support "thcount" format specifier on Xenial |
description: | updated |
Status changed to 'Confirmed' because the bug affects multiple users.