cron.weekly issue #31: Podcasting, ImageMagick, OwnCloud, DWF, Serverless, cronjobs and more!

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Mattias Geniar, June 05, 2016

Follow me on Twitter as @mattiasgeniar

Welcome to cron.weekly issue #31 for Sunday, June 5th, 2016.

A lot of content for getting started with Linux this time, if you’re new or want to learn more, make sure to read on. Also, I launched something new and I’m pretty excited about that!

I started a podcast

A few weeks ago, I started a podcast called SysCast. The first 3 episodes have been recorded and I think you might like them.

As on you can tell by the numbering scheme, I plan to stop at 999 episodes. 🙂

If you’ve got interesting and fun topics you’d like to see featured on the show, do let me know! You can subscribe via your favourite podcasting application by just searching for SysCast, or look at the website for more details.


Kickstarter: ImageMagick alternative ‘Imageflow’

This Kickstarter wants to launch an ImageMagick alternative that’s 10x faster. You can help fund the project that’ll be available entirely as open source.

PyCon 2016 videos online

Lots of content is available from the Python conference PyCon, held in Portland last week. Over 30 high-quality videos on Python talks.

Docker Volume Driver for VMware vSphere

I’m exciting about this news: VMware is launching a Volume Driver for Docker, currently in tech preview. That means integration of Docker containers with a persistent storage on VMware is about to become easier and more highly available.

Why did ArchLinux embrace systemd?

A really interesting Reddit thread where one of the maintainers of Arch’s init scripts explains their move to systemd. If you’re interested in knowing some of the background, make sure to click through.

Introducing The DWF project: Vulnerability reporting done the open source way

Red Hat has launched a community effort to improve CVE identifiers for vulnerabilities, called DWF: Distributed Weakness Filing. Now, CVE identifiers no longer need to be requested, the DWF project can assign those numbers itself with help from the community.

WTF is operations? #serverless

The last few months, the term “serverless” has been used more and more. This post debunks some of those myths and explains the ideas behind “#serverless”. (Spoiler: there are still servers to manage)

How the Internet works: Submarine fiber, brains in jars, and coaxial cables

While not directly linux/open source, this is a very good article on how the internet works with some rare insights into subsea cable landing sites.

Myths about /dev/urandom

There are a few things about /dev/urandom and /dev/random that are repeated again and again. Still they are false. This post explains what they are and why they’re false.

OwnCloud gets forked into NextCloud

The OwnCloud project was forked into NextCloud, causing a whole world of drama to follow. Normally, competition motivates innovation and speed of development, this just may turn out quite different.

Tools & Projects


rsnapshot is a filesystem snapshot utility based on rsync. rsnapshot makes it easy to make periodic snapshots of local machines, and remote machines over ssh. The code makes extensive use of hard links whenever possible, to greatly reduce the disk space required.


colout is a simple command to add colors to a text stream in your terminal.  You can think of colout as an alternative to ‘grep –color’ which will preserve the surrounding context, whith more powerful coloring capabilites.

IPv6 support coming to fail2ban

The next release of fail2ban will, finally, support IPv6. Fail2ban can read your log files, search for patterns and block the offending IPs.


CoreOS introduces Torus, a new open source distributed storage system designed to provide reliable, scalable storage to container clusters orchestrated by Kubernetes, the open source container management system.

Guides & Tutorials

10 Example of lsof commands in UNIX and Linux

‘lsof’ is a very powerful command in Linux, used to trace which processes keep which files ‘busy’.

DNF / YUM History

A good reminder on how to use the yum or dnf package manager ‘history’ command to undo a wrong installation or removal of a package.

Common shell script mistakes

A lot of practical tips about styling, proper variable matching, needless logic, globbing, adding robustness to your shell scripts, …

Linux From Scratch

Linux From Scratch (LFS) is a project that provides you with step-by-step instructions for building your own custom Linux system, entirely from source code.

How To Set Up Docker Monitoring

A very practical and detailed guide on monitoring Docker containers, based on Grafana, Cadvisor and InfluxDB. All tools and configs are available on GitHub.

Implementing ‘GOTO’ in Bash

A fun experiment: implementing the GOTO routine in a Bash script.

Understanding Cattle, Swarm and Kubernetes in Rancher

Rancher is a new platform for running container. Cattle was their first container orchestration implementation, this blogpost compares that to Kubernetes and Docker Swarm.

How (and Why) to Log Your Entire Bash History

The author advocates logging all your bash history permanently and shares a set of scripts and commands to help you with that.

Learn Docker by building a Microservice

A very practical guide on getting started with Docker. Since Docker “motivates” the use of microservices in multiple containers, this post is explained by building a microservice yourself.

A quick introduction to Consul, Kubernetes, Sysdig Cloud and Codeship as container tools.

Limit the runtime of a cronjob or script

This post explains how you can limit a cronjob (or any script, for that matter) in execution time. Using the ‘timeout’ command, you can kill a process whenever a time limit is reached.

Using linux utilities in a real world usecase

The tools ‘sed’ and ‘awk’ explained with a very practical, real world use case.

Learning Linux: Linux Journey

An absolutely stunningly beautiful website for learning linux and getting started. Really nice flow to getting you introduced with the distributions, the CLI and Linux in general.

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