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

Canonical
28 April 2026

Run NVIDIA Nemotron 3 Nano Omni locally in a single command

AI AI

Today, NVIDIA introduced the NVIDIA Nemotron™ 3 Nano Omni, a highly-efficient multimodal model designed to understand and reason across video, audio, images, and language.  Canonical is enabling immediate access to Nemotrom 3 Nano Omni through inference snaps: pre-packaged AI inference runtimes distributed as snap packages for consistent ...

Johann Wolf
27 April 2026

Why Web Engineering is great

Ubuntu Article

Like many software engineers, one of my first software development experiences started with creating my own web page. Since that time 20+ years ago, a lot has changed in the web landscape. Having worked a lot in web since then, I’d like to take a moment to reflect on what I think makes web great! ...

Ishani Ghoshal
27 April 2026

Ubuntu 16.04 LTS has reached the end of standard Expanded Security Maintenance with Ubuntu Pro. Here are your options.

Ubuntu Article

Ubuntu 16.04 LTS (Xenial Xerus) reached the end of its five-year Expanded Security Maintenance (ESM) window in April 2026. If you are still running 16.04, it is critical to address your support status to ensure continued security and compliance. Your support options Now that 16.04 is in its Legacy phase, you have two primary paths: ...