Hostname Completion

Shell Courtesy of Pete in work. To enable hostname auto completion in Bash, do the following: dig pop @dns.server.tld axfr | awk '$4 ~ /\yA\y/ && gsub(/.$/,"",$1) {print $1}' > ~/.hosts If you would prefer to filter out hosts e.g. dev and... » More

Querying Zookeeper from Python

Install the prerequisites. Below works for Debian-based distros such as Ubuntu/Mint: Install python libraries: Example code below shows making a connection, getting the names of some child nodes and pulling info from each of those child... » More

Install check_mk on Ubuntu 18.04

Ubuntu 18.04 includes check-mk in the repository version but it is an older version 1.2.8 (at the time of writing). Download check mk raw (get the latest stable URL from the website) : Try installing it: You may get dependency issues which can... » More

iDRAC 9 Set Physical Disk to Non-RAID

In the update from iDRAC 8 to iDRAC 9 it has been infuriating searching the 'Storage' menu only to discover that the storage is managed under 'Configuration > Storage Configuration'  I'm convinced the user experience could be better! At the very... » More

Clearing old Journald Logs

Journald logs can be cleared by timescale or size as follows. Keep only 5 days worth of logs journalctl --vacuum-time=5d Retain only the past 500 MB: journalctl --vacuum-size=500M

Checking if Puppet is Disabled

The puppet agent can be disabled from running with: And it can be re-enabled with: But to check if puppet is currently disabled there is no check command. Instead look for the existence of the agent_disabled.lock file under: For the systems I... » More

Exclude Directories for Disk Usage (du)

ncdu I sometimes want to omit directories from my disk usage (du -sh *) checks. This includes virtual files systems such as proc / dev and also mounts to other filesystems (data in the example below). This is what works for me: The equals sign appears to... » More

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Joining Multi-line Output with Paste

Shell I was checking the memory on approximately 140 servers using ansible: but the output appears over several lines e.g. but what I wanted was the server name and the total memory available. So I first grepped the output to remove the lines I didn't... » More

Datanode denied communication with namenode

In a Cloudera cluster we had a few nodes reporting the following error message in the logs under hadoop-cmf-hdfs-DATANODE-whatever.com.log.out The error included: Datanode denied communication with namenode because the host is not in the... » More