How to put Hadoop datanodes in maintenance state
Use JSON-based configuration format for Hadoop datanodes to create a whitelist and control put these in normal, decommissioned or maintenance state. This functionality allows using maintenance mode...
View ArticleHow to wait until service is running inside ansible playbook
Wait until service is stopped or running inside ansible playbook. Sample playbook to visualize the solution. --- - hosts: localhost vars: local__service: ssh tasks: - block: - name: "Stop {{...
View ArticleHow to use solid color instead of picture on Ubuntu desktop
Use solid color instead of picture on Ubuntu desktop. Ensure that picture uri is undefined. $ gsettings set org.gnome.desktop.background picture-uri "" Set background color to red. $ gsettings set...
View ArticleHow to update reconfigurable properties on Hadoop node
Update reconfigurable properties on Hadoop node without restart. Display reconfigurable properties on namenode. $ sudo -u hadoop -i hdfs dfsadmin -reconfig namenode namenode.example.org:9000 properties...
View ArticleHow to display ZooKeeper state for each server
Display ZooKeeper state for each server using the four-letter commands. Use the following shell script to execute the four-letter command mntr that will output a list of variables that could be used...
View ArticleHow to remove trash icon from sidebar on Ubuntu desktop
Remove trash icon from sidebar on Ubuntu desktop. By default there is a trash icon visible on the left sidebar. Use GSettings configuration tool to remove it. $ gsettings set...
View ArticleHow to install privacy focused fork of Firefox
Install LibreWolf a fork of Firefox that is focused on privacy, security and freedom. Add a dedicated repository. $ echo "deb [arch=amd64 signed-by=/etc/apt/trusted.gpg.d/librewolf.gpg] \...
View ArticleHow to distribute data evenly across all disks on a Hadoop datanode
Distribute data evenly across all disks on a Hadoop datanode. Inspect diskbalancer command which moves blocks from one disk to another. $ sudo -u hadoop -i hdfs diskbalancer -help usage: hdfs...
View ArticleHow to manage Kafka topics using command-line
Manage Kafka topics using command-line. This blog post is based on my experience with the Ansible automation engine, but I will keep things agnostic to any particular automation software, so you can...
View ArticleHow to execute multiple Ansible tasks once per group
Execute multiple Ansible tasks once per group and use a dedicated variable to store custom data. Define hosts that will contain multiple application clusters. $ cat hosts [application:children]...
View ArticleHow to identify a GNOME application that acquired an inhibitor lock
Identify a GNOME application that acquired an inhibitor lock and blocks power-off or reboot operation. The issue Try to power-off or reboot the machine. $ sudo reboot Operation inhibited by "milosz"...
View ArticleHow to define idle delay on Ubuntu desktop
Define idle delay (blank screen) on Ubuntu desktop. By default idle delay (blank screen) can be set from 1 to 15 minutes, or simply disabled. Get current idle delay (blank screen) value using seconds....
View ArticleHow to incorporate EDID into initrd image
Incorporate EDID (Extended Display Identification Data) into initrd (initial ramdisk) image. Extract Extended Display Identification Data Install required software on a Linux machine that can properly...
View ArticleHow to define favorite applications on Ubuntu desktop
Define favorite applications on Ubuntu desktop using command-line utility. Get current favorite applications. $ gsettings get org.gnome.shell favorite-apps ['org.gnome.Nautilus.desktop',...
View ArticleHow to use PKCS #12 as ZooKeeper truststore
PKCS #12 format works fine when used to provide ZooKeeper keystore, but additional steps are needed to use it for a dedicated truststore. You will get the following error when you try to use PKCS #12...
View ArticleHow to use DPMS to turn screen on or off
Use DPMS (Display Power Management Signaling) to turn screen on or off. Display DPMS settings. $ xset q Keyboard Control: auto repeat: on key click percent: 0 LED mask: 00000002 XKB indicators: 00:...
View ArticleHow to extend LVM logical volume without free space on the root partition
Extend LVM logical volume without free space on the root partition. Sometimes you can encounter such a problem when there is no free space on the root partition, so the volume group configuration...
View ArticleHow to keep a list of permanent ARP entries
Keep a list of permanent ARP entries using the arp utility. Install net-tools package. $ sudo apt install net-tools Store permanent ARP entries in a /etc/ethers file. $ cat <<EOF | sudo tee...
View ArticleHow to inspect LVM history using metadata archives
Inspect LVM history using metadata archives. Inspect LVM history on a regular Ubuntu instance. $ sudo bash -c "cat /etc/lvm/archive/*" | \ awk -F= '$0 ~ /^creation_time =|^description =/ { print $2 }'...
View ArticleHow to determine Kafka version using command-line utilities
Determine Kafka version using command-line utilities. Determine Kafka version by checking runtime class. $ /opt/kafka/kafka/bin/kafka-run-class.sh kafka.Kafka --version 2.8.0 (Commit:ebb1d6e21cc92130)...
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