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: apt-get install libzookeeper-mt-dev Install python libraries: pip install zkpython pykeeper Example code below shows making a connection, getting the names of some... » 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) : wget... » 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: puppet disable "Some message here" And it can be re-enabled with: puppet enable But to check if puppet is currently disabled there is no check command. Instead look for the existence of the... » 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: du... » More

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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