Execute gradle task on sub projects

All of the ways mentioned by Mark can be used but all of them have some cons. So I am adding one more option:

4. Switching the current project

gradle -p other hello

This switches the "current project" and then runs all tasks named hello under the current project.

Not entirely sure which of these you're after, but they should cover your bases.

1. Calling the tasks directly

You should just be able to call

gradle :other/projC:hello :other/projD:hello

I tested this with:

# Root/build.gradle
allprojects {
    task hello << { task -> println "$task.project.name" }
}

and

# Root/settings.gradle
include 'projA'
include 'projB'
include 'other/projC'
include 'other/projD'

2. Only creating tasks in the sub projects

Or is it that you only want the task created on the other/* projects?

If the latter, then the following works:

# Root/build.gradle
allprojects {
    if (project.name.startsWith("other/")) {
        task hello << { task -> println "$task.project.name" }
    }
}

and it can then be called with:

$ gradle hello
:other/projC:hello
other/projC
:other/projD:hello
other/projD

3. Creating a task that runs tasks in the subprojects only

This version matches my reading of your question meaning there's already a task on the subprojects (buildJar), and creating a task in root that will only call the subprojects other/*:buildJar

allprojects {
    task buildJar << { task -> println "$task.project.name" }
    if (project.name.startsWith("other/")) {
        task runBuildJar(dependsOn: buildJar) {}
    }
}

This creates a task "buildJar" on every project, and "runBuildJar" on the other/* projects only, so you can call:

$ gradle runBuildJar
:other/projC:buildJar
other/projC
:other/projC:runBuildJar
:other/projD:buildJar
other/projD
:other/projD:runBuildJar

Your question can be read many ways, hope this covers them all :)