How to use exec() output in gradle

Question

I am trying to implement a gradle task to dynamically create a buildsignature.properties file from a series of environment variable values and shell executions. I have it mostly working, but I can't seem to get the output of the shell commands. Here's my task... ``` task generateBuildSignature << { ext.whoami = exec() { executable = "whoami" } ext.hostname = exec() { executable = "hostname" } ext.buildTag = System.env.BUILD_TAG ?: "dev" ant.propertyfile( file: "${buildDir}/buildsignature.properties", comment: "This file is automatically generated - DO NOT EDIT!" ) { entry( key: "version", value: "${project.version}" ) entry( key: "buildTimestamp", value: "${new Date().format('yyyy-MM-dd HH:mm:ss z')}" ) entry( key: "buildUser", value: "${ext.whoami}" ) entry( key: "buildSystem", value: "${ext.hostname}" ) entry( key: "buildTag", value: "$ext.buildTag" ) } } ``` But the resulting properties field does not get the desired results for buildUser and buildSystem. ``` #This file is automati…

Accepted Answer

This post describes how to parse the output from an `Exec` invocation. Below you'll find two tasks that run your commands.

```
task setWhoamiProperty {
    doLast {
        new ByteArrayOutputStream().withStream { os ->
            def result = exec {
                executable = 'whoami'
                standardOutput = os
            }
            ext.whoami = os.toString()
        }
    }
}

task setHostnameProperty {
    doLast {
        new ByteArrayOutputStream().withStream { os ->
            def result = exec {
                executable = 'hostname'
                standardOutput = os
            }
            ext.hostname = os.toString()
        }
    }
}

task printBuildInfo {
    dependsOn setWhoamiProperty, setHostnameProperty
    doLast {
         println whoami
         println hostname
    }
}
```

There's actually an easier way to get this information without having to invoke a shell command.

Currently logged in user: `System.getProperty('user.name')`

Hostname: `InetAddress.getLocalHost().getHostName()`

How to use exec() output in gradle

Solution

Problem