In Gradle, is there a better way to get Environment Variables?

Question

In several Tasks, I reference jars in my home folder.

Is there a better way to get Environment Variables than

ENV = System.getenv()
HOME = ENV['HOME']

task copyToServer(dependsOn: 'jar', type: Copy) {

 from 'build/libs/'
 into HOME + "/something/plugins/"
}

This sets $HOME but I was hoping that I missed some magic from the documentation.

Plume

Be aware that before environment variable can be seen and used by Gradle, it needs to be exported, ex. $ export FOO=bar. – Aldred

There's something I'm missing here... I have to put def HOME: Gradle 4.4.1 Project does not have a HOME property or an ENV property. Could be something which dropped out ... ? – Selfrighteous

Answer 1

Well; this works as well:

home = "$System.env.HOME"

It's not clear what you're aiming for.

Libelous

or to your usage: into "${System.env.HOME}/something/plugins" – Secular

Be aware that "$System.env.FOO" returns String with value "null", if the environment variable FOO is not defined as a system environment variable. It might be confusing since logging a String with value "null" to console will print the same output as null variable. – Azure

or just home = System.env.HOME ? – Pastiness

If you are trying to get an environment variable that might not be set, it would be better to use System.getenv('VAR') which returns null if not assigned. If you use "$System.env.VAR" then it will return the string "null". – Potts

There's something I'm missing here... I have to put def home: Gradle 4.4.1 Project does not have a home property. Could be something which dropped out ... ? – Selfrighteous

@Potts You can also use System.env.VAR. The reason "$System.env.VAR" returns (the string) "null" rather than null is because of string interpolation, not because of using System.env in place of System.getenv. Using "${System.getenv('VAR')}" has the exact same problem. – Sissel

Answer 2

I couldn't get the form suggested by @thoredge to work in Gradle 1.11, but this works for me:

home = System.getenv('HOME')

It helps to keep in mind that anything that works in pure Java will work in Gradle too.

Typhon

Not sure why but I could only get the System.getenv('HOME') version to work for me. The other version kept returning null – Extranuclear

Did you use single quotes instead of double by mistake, perhaps? – Pastiness

this is better than the answer: https://mcmap.net/q/127134/-in-gradle-is-there-a-better-way-to-get-environment-variables, because it returns null instead of "null" in case it does not exist. – Eldridgeeldritch

As of new Gradle versions, it's better to use a provider, specially if you're doing it on the initialization or configuration phase: def homeProvider = providers.environmentVariable('HOST') – Fading

Answer 3

This is for Kotlin DSL (build.gradle.kts):

val myVariable = System.getenv("MY_VARIABLE_NAME") ?: "my default value"

OR

val myVariable = System.getenv("MY_VARIABLE_NAME") ?: error("Env variable not found")

OR

val environment = System.getenv()
val myVariable = environment["MY_VARIABLE_NAME"] ?: "my default value"
// OR val myVariable = environment["MY_VARIABLE_NAME"] ?: error("Env variable not found")

Jerald

Answer 4

In android gradle 0.4.0 you can just do:

println System.env.HOME

classpath com.android.tools.build:gradle-experimental:0.4.0

Jezabel

thoredge said that 4 years before your answer! – Selfrighteous