Skip to main content

How to check if environment variable is set using shell script?

If you are wondering how can we check whether an environment variable is set or not in the system, here are few methods :

1. Manually
a. Run “set” command on the shell prompt, it will list out all the variables set in the system :
# set
b. Run “echo” command on the shell to print the value of the environment variable :
# echo $<environment variable>

2. Through Shell Script
Let say we intent to check whether environment variable “envVar” is set or not?

a. Method 1 – checking if “envVar” is set to “” (no value) :
if [ "$envVar" == "" ]
then
echo “envVar is not set”
else
echo “envVar is set”
fi

b.Method 2 – checking if “envVar” is non NULL :
if [ -n "$envVar" ]
then
echo “envVar has non NULL value, it is set.”
else
echo “envVar has NULL value, it is not set.”
fi
Labels:

Comments

Post a Comment

Popular posts from this blog

Exploring Node.js Internals

I found a great article explaining Node JS internals, must read :

https://www.smashingmagazine.com/2020/04/nodejs-internals/


Some other articles :

Introduction to Node.jsBeing an official website, Node.dev explains what Node.js is, as well as its package managers, and lists web frameworks built on top of it.“JavaScript & Node.js”, The Node Beginner BookThis book by Manuel Kiessling does a fantastic job of explaining Node.js, after warning that JavaScript in the browser is not the same as the one in Node.js, even though both are written in the same language.Beginning Node.jsThis beginner book goes beyond an explanation of the runtime. It teaches about packages and streams and creating a web server with the Express framework.LibUVThis is the official documentation of the supporting C++ code of the Node.js runtime.V8This is the official documentation of the JavaScript engine that makes it possible to write Node.js with JavaScript. x
Post a Comment
Read more

JUnit – Run unit test in an Sequence / Order

In JUnit, we can use @FixMethodOrder(MethodSorters.xxx) to run the test methods in a sequence or order.

import org.junit.FixMethodOrder;import org.junit.Test;import org.junit.runners.MethodSorters;importstatic org.hamcrest.CoreMatchers.is;importstatic org.junit.Assert.assertThat;//Sorts by method name@FixMethodOrder(MethodSorters.NAME_ASCENDING)publicclassExecutionOrderTest{@TestpublicvoidtestB(){assertThat(1+1,is(2));}@Testpublicvoidtest1(){assertThat(1+1,is(2));}@TestpublicvoidtestA
Post a Comment
Read more