Linux Chamber

We must reboot our server when we install a new kernel or libraries, Ubuntu Linux can tell you if the system needs a reboot when you login as root user. *** System restart required *** The above warning will appear on the login screen, we may miss this warning. So here is the simple script for administrators to find exactly when the system requires reboot. You can manually find the file: /var/run/reboot-required, which indicates System restart required. Instead of a manual search, you can use below script to identify the ubuntu notification of 'system restart required’ at every login and never miss the warning. Add the below lines in the file: /root/status.sh #!/bin/bash if [ -f /var/run/reboot-required ] then    echo -e "\033[33;31m[*** Hello $USER, you must reboot your machine ***]\033[0m" else    echo -e "\033[33;32m\n*** System reboot is NOT required now ***\n`cat /var/lib/update-notifier/updates-available`\n\033[0m" fi Now we

Systemd is a system and service manager for Linux operating systems. It is designed to be backwards compatible with SysV init scripts, and provides a number of features such as parallel startup of system services at boot time, on-demand activation of daemons, support for system state snapshots, or dependency-based service control logic. It may refer to all the packages, utilities and libraries around daemon. Systemd was designed to overcome the shortcomings of init and itself is a background processes which is designed to start processes in parallel, thus reducing the boot time and computational overhead. It has a lot other features as compared to init. Why there was a need to replace init? A init process starts serially i.e., one task starts only after the last task startup was successful and it was loaded in the memory. This often resulted into delayed and long booting time. However, systemd was not designed for speed but for getting the things done neatly wh

Here are the simple steps for the installation of pssh on CentOS7: pssh is a program for executing ssh in parallel on a number of hosts. It provides features such as sending input to all of the processes, passing a password to ssh, saving output to files, and timing out. Install epel: # yum install epel-release Install pssh: # yum install pssh create pssh_hosts.txt file and enter the hosts need to target: # cat pssh_hosts.txt # write hosts per line like follows #user@target_ip root@192.168.100.100 we should do key-pair between the master host and targets, this is the only way to get things done.(simply login the target from master node for Host key verification) # ssh root@192.168.100.100 Test with single commands # pssh -h /path/to/pssh_hosts.txt -A -O PreferredAuthentications=password -i "hostname" # pssh -h /path/to/pssh_hosts.txt -A -O PreferredAuthentications=password -i "uptime" Output: [root@mas

Here is a Step by Step Guide to install rundeck on ubuntu 17.04(zesty): As we know 'Rundeck is open source software that helps you automate routine operational procedures in data center or cloud environments, it allows you to run tasks on any number of nodes from a web-based or command-line interface.' from the previous post Rundeck installation on CentOS . I'm installing rundeck on ubuntu 17.04(zesty)(my server ip is: 192.168.225.231) pre-requirements: Installing java: # apt-get install openjdk-8-jdk Setting up java home: Add the below contents in file: /etc/profile.d/java.sh #!/bin/bash JAVA_HOME=/usr/bin/java PATH=$JAVA_HOME/bin:$PATH export PATH JAVA_HOME export CLASSPATH=. # source /etc/profile.d/java.sh Firewall setup: We can enable the ufw and allow port 4440. Let us download the rundeck package(.deb) from: http://rundeck.org/downloads.html we can start the rundeck installation: # dpkg -i rundeck-2.8.2-1-GA.deb

Rundeck is all about ....! Well, Rundeck is open source software that helps you automate routine operational procedures in data center or cloud environments, it allows you to run tasks on any number of nodes from a web-based or command-line interface. Rundeck also includes other features that make it easy to scale up your automation efforts including: access control, workflow building, scheduling, logging, and integration with external sources for node and option data. Refer introduction and essential-concepts URL for more details. Pre-requirements and preparing the server to install rundeck: The following operating systems are known to support Rundeck: Linux: Most recent distributions are likely to work Windows: XP, Server and above Mac OS X 10.4 or later     Root (or Administrator on Windows) is not required or recommended. We recommend using a dedicated user account such as "rundeck". If there is need for root access, please set