Friday, October 21, 2016

Oracle Linux - Checking installed package

In some cases you want to verify if a package is installed on your Oracle Linux instance within a bash script. You query what is installed by using the "list installed" option for the yum command. However, this is giving you a more human readable result and not something that works easy in a the flow of a script. In essence you would like to have a boolean value returned to tell you if a package is installed or not on your Oracle Linux instance.

The below code example is a bash script that will exactly do so. Within the example you see the packageInstalled function which takes a variable for the package name you are looking for. The result will be true or false.

#!/bin/bash

function packageInstalled () {
     numberOfPackages=`yum list installed | grep $1 | wc -l`
     if [ "$numberOfPackages" -gt "0" ];
       then
           echo "true"
     else
         echo "false"
     fi
}

packageInstalled wget

In the example we are checking the installation of the wget package. You can change wget for whatever you need to be sure is installed. Using this building block function can help you to write a more complex script for installing packages when needed. 
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