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

Benjamin Ryzman
24 February 2026

Building quantum-safe telecom infrastructure for 5G and beyond

private mobile network Article

coRAN Labs and Canonical at MWC Barcelona 2026 At MWC Barcelona 2026, coRAN Labs and Canonical are presenting a working demonstration of a cloud-native, quantum-safe telecom platform for 5G and beyond 5G networks. This is not a conceptual exercise. It is a full 5G System (5GS) deployment with post-quantum cryptography embedded across the ...

Philip Williams
18 February 2026

Predict, compare, and reduce costs with our S3 cost calculator

Ceph Article

Previously I have written about how useful public cloud storage can be when starting a new project without knowing how much data you will need to store. However, as datasets grow over time, the costs of public cloud storage can become overwhelming. This is where an on premise, or co-located, self-hosted storage system becomes advantageous ...

Yanisa Haley Scherber
17 February 2026

A year of documentation-driven development

Ubuntu Article

For many software teams, documentation is written after features are built and design decisions have already been made. When that happens, questions about how a feature is understood or used often don’t surface until much later.  A little over one year ago, our team began to recognize this pattern in our own work. Features generally ...