cron.weekly issue #42: PowerShell, Bus1, SAM, Minisign, flyingwhale & much more!

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Mattias Geniar, August 21, 2016

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Welcome to cron.weekly issue #42 for Sunday, August 21st, 2016.

If you happen to be at Laracon EU next week, come say hi! I’ll be speaking about Varnish on Tuesday afternoon.

It’s a fully packed edition again this time, so take a coffee, relax and have fun reading!


PowerShell is open sourced and is available on Linux

My-oh-my: the Windows shell, PowerShell, is now available on Linux and Mac. PowerShell allows you to not only pipe text from command to command, but pass entire objects, giving it more flexibility to automate tasks.

Debian turns 23 years

Happy birthday, Debian!

Maintainers Wanted

We’ve all started a project and abandon it at one point. This repository shows a list of projects that are looking for new maintainers, because the current maintainer can no longer do so. If there’s anything in there you like, contact the owner!

What is copyleft?

The term has been used more and more lately. We all know copyright with the different open source licenses, but what does copyleft mean?

Bus1: a new Linux interprocess communication proposal

The Linux kernel may get an alternative to IPC (Inter Process Communication) called bus1, in order to address several of the shortcomings of the current IPC implementation.

Differentiating Communication Styles of Leaders on the Linux Kernel Mailing List (PDF)

This is a bit of a weird one, but this paper analysed the Linux kernel mailing list and maps out the behaviour of key figures (ie: Linus Torvalds) to summarise their communication style, how they compare to others etc. Remarkable: the table about most often used words (spoiler: lots of swearing, page 4).

Tools & Projects

Otto goes end-of-life

Hashicorp is retiring the otto tool, which was used to develop and deploy applications.

Go 1.7

A new release of the Go programming language: more compiler optimisations, faster compile times, around 20% smaller binaries and better garbage collection for faster applications.


Gradle is a build tool with a focus on build automation and support for multi-language development.

System Architecture Mapper (SAM)

SAM is an interactive network-traffic mapping tool. It uses information from the connection logs of routers and draws a map of the connections between hosts. Think of it as a “blind system architecture drawer”, by just looking at the network traffic, it can draw out a map of the system(s) and how they communicate with each other. Fascinating!


Minisign is a dead simple tool to sign files and verify signatures.


This is a clever one: a container as a command line tool from many package management systems. Instead of typing “npm install bower”, you type “whale npm install bower”: this tool will spin up a docker container, run the npm install and symlink a binary called bower to your bin-path. Every time you start the newly installed tool, it’ll run that container. No more dependency garbage on your device!

Jenkins Job DSL plugin

Instead of making Jenkins job in the GUI, you can do so with config files and programmatically. This makes it more ideal to distribute your configs and version-control your Jenkins jobs.


A parallel implementation of gzip for modern multi-processor, multi-core machines.

Guides & Tutorials

Context aware MySQL pools via HAProxy

Some pretty clever engineering by GitHub: they use HAProxy with content checks to determine if a MySQL slave is ready to serve traffic. If the replication lag is too high, the node will flag itself as unavailable leaving the task for others.

Extracting data from Wikipedia using curl, grep, cut and other shell commands

A nice article about the power of just a few simple Linux commands: curl, grep, cut, uniq & sort to get unstructured data (like an HTML page) and strip it down to just the bare essentials.

Setup, GPG & Git to sign commits on GitHub

A guide on getting started with GPG for signing your commits. While I applaud these guides for adding security, it still shows how complicated GPG really is.

Colorized man pages

This handy little bash snippet adds color to your manpages, by setting the different environment variables that are being read by the man page.

How you tell what signals a Linux process is ignoring

A nice explanation on reading the /prod/$pid/status output and interpreting from that which kill signals a particular process will catch.

A clean start – How to prepare a minimal Debian template for LXC containers

Some good pointers on what to remove from a system to make it as small as possible, in this case for use as a container base template.

The 101 of ELF Binaries on Linux: Understanding and Analysis

An extensive dive into ELF (Executable Linkable Format) files: for security incident response, development, and better understanding.


Black Hat USA 2016

Last week the Black Hat hacker conference was held, the first videos are already online. If you’re into security, you’ll love these!

Linux Performance Analysis and Tools: Brendan Gregg

Remember that performance diagram from last week? That same author also gave a talk a few years ago about finding bottlenecks in Linux: CPU, memory, disk I/O, network, … all with practical examples.

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