Skip to main content
  1. Blog
  2. Article

Canonical
on 17 June 2014

OpenStack One-Liners

One-line bash commands for managing, deploying and testing OpenStack and related components, hypervisors and containers.  Some simple and obvious, some cool and questionable, hopefully all useful.  Check back on this post, I’ll likely add more. #1 – Watch Nova Compute for Non-Active Instances on Openstack Outputs total instance count and non-active instances. Useful for keeping an eye on potential problem VMs in a PAUSED, ERROR, SHUTOFF or other non-active state. Command: watch --interval=1 'nova list --all-tenants | wc -l && nova list --all-tenants | grep -v "ACTIVE"' #2 – Ping a List of Hosts Forever:  1-Line Loop A simple one-line while loop containing a for loop to ping a list of hosts each with one packet, followed by a 1/4 second iteration delay and an output text filter. Command: while true; do for h in bcu vxu rbu; do ping ${h} -c 1 | grep ttl; sleep 0.25; done; done;   #3 – Watch Cinder Volumes and Snapshots and Glance Images in Openstack Useful for working with volumes, snapshots and images in small Openstack deployments. watch --interval=1 "cinder list && cinder snapshot-list && glance image-list"   #4 – Watch Linux Containers and Directory-Backed Storage I find this one handy when I need to monitor LXC containers on Ubuntu Server – Precise Pangolin, Trusty Tahr, Utopic Unicorn and later.  The Ubuntu Server Guide has a detailed section on LXC usage. watch "sudo lxc-ls --fancy --nesting && sudo ls -Ralh /var/lib/lxc/"   #5 – Watch Your Disk Space Disappear This is a tail-style output of the free space on /. while true; do df -h / | grep '/' | awk '{ print $4 }'; sleep 1; done 6.1G 6.1G 6.0G 6.0G 5.9G 5.8G 5.7G 5.7G  

Related posts

Kola Ojoodide
26 June 2026

Challenges designers face in open source (and how to fix them)

Design open source

Open source powers up to 90% of modern software, yet many projects lack usability. Canonical’s Design team surveyed 115 cross-functional professionals to uncover the 4 core challenges UI/UX designers face when contributing, and how maintainers can solve them. ...

Bertrand Boisseau
24 June 2026

Anbox Cloud on C4A metal: Android, at scale, without friction

Ubuntu Article

Why C4A metal is a great place to run Android and why Anbox Cloud makes that practical. If you’ve spent even a small portion of time working with Android development at scale, you’ve likely encountered some pinch points. The platform was built for Arm-based devices, mobile physical hardware, and tightly controlled system environments. Clo ...

Rajan Patel
23 June 2026

Canonical announces live kernel patching for Arm64

Security Article

Canonical Livepatch now officially supports Arm64, further expanding its security patching automation capabilities. For the first time, Ubuntu on an Arm64 machine can apply critical kernel updates, without service interruption or rebooting. Starting with Ubuntu Core 26 for Arm64, and for Ubuntu Core 20 and onwards for AMD64 machines, a wi ...