procps-ng 3.3.16

procps-ng version 3.3.16 was released today. Besides some documentation and library updates, there were a few incremental changes. Zombie Hunting with pgrep Ever wanted to find zombies? Perhaps processes with other states? pgrep has a shiny new runstate flag to help you which will match process against the runstate. I’m curious to see the use-cases

The sudo tty bug and procps

There have been recent reports of a security bug in sudo (CVE-2017-1000367) where you can fool sudo into thinking what controlling terminal it is running on to bypass its security checks.  One of the first things I thought of was, is procps vulnerable to the same bug? Sure, it wouldn’t be a security bypass, but it would be a normal sort of bug. A lot of programs  in procps have a concept of a controlling terminal, or the TTY field for either viewing or filtering, could they be fooled into thinking the process had a different controlling terminal?

Was I going to be in the same pickle as the sudo maintainers? The meat between the stat parsing sandwich? Can I find any more puns related somehow to the XKCD comic?

TLDR: No.

procps 3.3.12

The procps developers are happy to announce that version 3.3.12 of procps was released today. This version has a mixture of bug fixes and enhancements. This unfortunately means another API bump but we are hoping this will be fixed with the new library API coming soon.

procps is developed on gitlab and the new version of procps can be found at https://gitlab.com/procps-ng/procps/tree/newlib

procps 3.3.12 can be found at https://gitlab.com/procps-ng/procps/tags/v3.3.12

Sheepdog staring off a RAM sheep

Displaying Linux Memory

Memory management is hard, but RAM management may be even harder.

Most people know the vague overall concept of how memory usage is displayed within Linux. You have your total memory which is everything inside the box; then there is used and free which is what the system is or is not using respectively. Some people might know that not all used is used and some of it actually is free.  It can be very confusing to understand, even for a someone who maintains procps (the package that contains top and free, two programs that display memory usage).

So, how does the memory display work?

pidof lost a shell

pidof is a program that reports the PID of a process that has the given command line. It has an option x which means “scripts too”. The idea behind this is if you have a shell script it will find it. Recently there was an issue raised saying pidof was not finding a shell script. Trying it out, pidof indeed could not find the sample script but found other scripts, what was going on?

ps standards and locales

I looked at two interesting issues today around the ps program in the procps project. One had a solution and the other I’m puzzled about.

ps User-defined Format

Issue #9 was quite the puzzle. The output of ps changed depending if a different option had a hyphen before it or not.

First, the expected output

$ ps p $$ -o pid=pid,comm=comm
 pid comm
31612 bash

Next, the unusual output.

$ ps -p $$ -o pid=pid,comm=comm
pid,comm=comm
 31612

Linux 4.0 ate my docker images

I have previously written about the gitlab CI runners that use docker.  Yesterday I made some changes to procps and pushed them to gitlab which would then start the CI.  This morning I checked and it said build failed – ok, so that’s not terribly unusual. The output from the runner was:

gitlab-ci-multi-runner 0.3.3 (dbaf96f)
Using Docker executor with image csmall/testdebian ...
Pulling docker image csmall/testdebian ...
Build failed with Error: image csmall/testdebian: not found

Hmm, I know I have that image, it just must be the runner so, let’s see what images I have:

$ docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE

Now, I know I have images, I had about 10 or so of them, where did they go? I even looked in the /var/lib/docker directories and can see the json configs, what have you done with my images docker?