# Chapter 4. Using the Gradle Command-Line

This chapter introduces the basics of the Gradle command-line. You run a build using the gradle command, which you have already seen in action in previous chapters.

## 4.1. Executing multiple tasks

You can execute multiple tasks in a single build by listing each of the tasks on the command-line. For example, the command `gradle compile test` will execute the `compile` and `test` tasks. Gradle will execute the tasks in the order that they are listed on the command-line, and will also execute the dependencies for each task. Each task is executed once only, regardless of how it came to be included in the build: whether it was specified on the command-line, or as a dependency of another task, or both. Let's look at an example.

Below four tasks are defined. Both `dist` and `test` depend on the `compile` task. Running `gradle dist test` for this build script results in the `compile` task being executed only once.

Figure 4.1. Task dependencies

Example 4.1. Executing multiple tasks

`build.gradle`

    task compile {
        doLast {
            println 'compiling source'
        }
    }

    task compileTest(dependsOn: compile) {
        doLast {
            println 'compiling unit tests'
        }
    }

    task test(dependsOn: [compile, compileTest]) {
        doLast {
            println 'running unit tests'
        }
    }

    task dist(dependsOn: [compile, test]) {
        doLast {
            println 'building the distribution'
        }
    }

Output of `gradle dist test`

    > gradle dist test
    :compile
    compiling source
    :compileTest
    compiling unit tests
    :test
    running unit tests
    :dist
    building the distribution

    BUILD SUCCESSFUL

    Total time: 1 secs

Each task is executed only once, so `gradle test test` is exactly the same as `gradle test`.

## 4.2. Excluding tasks

You can exclude a task from being executed using the `-x` command-line option and providing the name of the task to exclude. Let's try this with the sample build file above.

Example 4.2. Excluding tasks

Output of `gradle dist -x test`

    > gradle dist -x test
    :compile
    compiling source
    :dist
    building the distribution

    BUILD SUCCESSFUL

    Total time: 1 secs

You can see from the output of this example, that the `test` task is not executed, even though it is a dependency of the `dist` task. You will also notice that the `test` task's dependencies, such as `compileTest` are not executed either. Those dependencies of `test` that are required by another task, such as `compile`, are still executed.

## 4.3. Continuing the build when a failure occurs

By default, Gradle will abort execution and fail the build as soon as any task fails. This allows the build to complete sooner, but hides other failures that would have occurred. In order to discover as many failures as possible in a single build execution, you can use the `--continue` option.

When executed with `--continue`, Gradle will execute every task to be executed where all of the dependencies for that task completed without failure, instead of stopping as soon as the first failure is encountered. Each of the encountered failures will be reported at the end of the build.

If a task fails, any subsequent tasks that were depending on it will not be executed, as it is not safe to do so. For example, tests will not run if there is a compilation failure in the code under test; because the test task will depend on the compilation task (either directly or indirectly).

## 4.4. Task name abbreviation

When you specify tasks on the command-line, you don't have to provide the full name of the task. You only need to provide enough of the task name to uniquely identify the task. For example, in the sample build above, you can execute task `dist` by running `gradle d`:

Example 4.3. Abbreviated task name

Output of `gradle di`

    > gradle di
    :compile
    compiling source
    :compileTest
    compiling unit tests
    :test
    running unit tests
    :dist
    building the distribution

    BUILD SUCCESSFUL

    Total time: 1 secs

You can also abbreviate each word in a camel case task name. For example, you can execute task `compileTest` by running `gradle compTest` or even `gradle cT`

Example 4.4. Abbreviated camel case task name

Output of `gradle cT`

    > gradle cT
    :compile
    compiling source
    :compileTest
    compiling unit tests

    BUILD SUCCESSFUL

    Total time: 1 secs

You can also use these abbreviations with the `-x` command-line option.

## 4.5. Selecting which build to execute

When you run the gradle command, it looks for a build file in the current directory. You can use the `-b` option to select another build file. If you use `-b` option then `settings.gradle` file is not used. Example:

Example 4.5. Selecting the project using a build file

`subdir/myproject.gradle`

    task hello {
        doLast {
            println "using build file '$buildFile.name' in '$buildFile.parentFile.name'."
        }
    }

Output of `gradle -q -b subdir/myproject.gradle hello`

    > gradle -q -b subdir/myproject.gradle hello
    using build file 'myproject.gradle' in 'subdir'.

Alternatively, you can use the `-p` option to specify the project directory to use. For multi-project builds you should use `-p` option instead of `-b` option.

Example 4.6. Selecting the project using project directory

Output of `gradle -q -p subdir hello`

    > gradle -q -p subdir hello
    using build file 'build.gradle' in 'subdir'.

## 4.6. Forcing tasks to execute

Many tasks, particularly those provided by Gradle itself, support incremental builds. Such tasks can determine whether they need to run or not based on whether their inputs or outputs have changed since the last time they ran. You can easily identify tasks that take part in incremental build when Gradle displays the text `UP-TO-DATE` next to their name during a build run.

You may on occasion want to force Gradle to run all the tasks, ignoring any up-to-date checks. If that's the case, simply use the `--rerun-tasks` option. Here's the output when running a task both without and with `--rerun-tasks`:

Example 4.7. Forcing tasks to run

Output of `gradle doIt`

    > gradle doIt
    :doIt UP-TO-DATE

Output of `gradle --rerun-tasks doIt`

    > gradle --rerun-tasks doIt
    :doIt

Note that this will force all required tasks to execute, not just the ones you specify on the command line. It's a little like running a `clean`, but without the build's generated output being deleted.

## 4.7. Obtaining information about your build

Gradle provides several built-in tasks which show particular details of your build. This can be useful for understanding the structure and dependencies of your build, and for debugging problems.

In addition to the built-in tasks shown below, you can also use the project report plugin to add tasks to your project which will generate these reports.

### 4.7.1. Listing projects

Running `gradle projects` gives you a list of the sub-projects of the selected project, displayed in a hierarchy. Here is an example:

Example 4.8. Obtaining information about projects

Output of `gradle -q projects`

    > gradle -q projects

    ------------------------------------------------------------
    Root project
    ------------------------------------------------------------

    Root project 'projectReports'
    +--- Project ':api' - The shared API for the application
    \--- Project ':webapp' - The Web application implementation

    To see a list of the tasks of a project, run gradle <project-path>:tasks
    For example, try running gradle :api:tasks

The report shows the description of each project, if specified. You can provide a description for a project by setting the `description` property:

Example 4.9. Providing a description for a project

`build.gradle`

    description = 'The shared API for the application'

### 4.7.2. Listing tasks

Running `gradle tasks` gives you a list of the main tasks of the selected project. This report shows the default tasks for the project, if any, and a description for each task. Below is an example of this report:

Example 4.10. Obtaining information about tasks

Output of `gradle -q tasks`

    > gradle -q tasks

    ------------------------------------------------------------
    All tasks runnable from root project
    ------------------------------------------------------------

    Default tasks: dists

    Build tasks
    -----------
    clean - Deletes the build directory (build)
    dists - Builds the distribution
    libs - Builds the JAR

    Build Setup tasks
    -----------------
    init - Initializes a new Gradle build. [incubating]
    wrapper - Generates Gradle wrapper files. [incubating]

    Help tasks
    ----------
    buildEnvironment - Displays all buildscript dependencies declared in root project 'projectReports'.
    components - Displays the components produced by root project 'projectReports'. [incubating]
    dependencies - Displays all dependencies declared in root project 'projectReports'.
    dependencyInsight - Displays the insight into a specific dependency in root project 'projectReports'.
    dependentComponents - Displays the dependent components of components in root project 'projectReports'. [incubating]
    help - Displays a help message.
    model - Displays the configuration model of root project 'projectReports'. [incubating]
    projects - Displays the sub-projects of root project 'projectReports'.
    properties - Displays the properties of root project 'projectReports'.
    tasks - Displays the tasks runnable from root project 'projectReports' (some of the displayed tasks may belong to subprojects).

    To see all tasks and more detail, run gradle tasks --all

    To see more detail about a task, run gradle help --task <task>

By default, this report shows only those tasks which have been assigned to a task group, so-called visible tasks. You can do this by setting the `group` property for the task. You can also set the `description` property, to provide a description to be included in the report.

Example 4.11. Changing the content of the task report

`build.gradle`

    dists {
        description = 'Builds the distribution'
        group = 'build'
    }

You can obtain more information in the task listing using the `--all` option. With this option, the task report lists all tasks in the project, including tasks which have not been assigned to a task group, so-called hidden tasks. Here is an example:

Example 4.12. Obtaining more information about tasks

Output of `gradle -q tasks --all`

    > gradle -q tasks --all

    ------------------------------------------------------------
    All tasks runnable from root project
    ------------------------------------------------------------

    Default tasks: dists

    Build tasks
    -----------
    clean - Deletes the build directory (build)
    api:clean - Deletes the build directory (build)
    webapp:clean - Deletes the build directory (build)
    dists - Builds the distribution
    api:libs - Builds the JAR
    webapp:libs - Builds the JAR

    Build Setup tasks
    -----------------
    init - Initializes a new Gradle build. [incubating]
    wrapper - Generates Gradle wrapper files. [incubating]

    Help tasks
    ----------
    buildEnvironment - Displays all buildscript dependencies declared in root project 'projectReports'.
    api:buildEnvironment - Displays all buildscript dependencies declared in project ':api'.
    webapp:buildEnvironment - Displays all buildscript dependencies declared in project ':webapp'.
    components - Displays the components produced by root project 'projectReports'. [incubating]
    api:components - Displays the components produced by project ':api'. [incubating]
    webapp:components - Displays the components produced by project ':webapp'. [incubating]
    dependencies - Displays all dependencies declared in root project 'projectReports'.
    api:dependencies - Displays all dependencies declared in project ':api'.
    webapp:dependencies - Displays all dependencies declared in project ':webapp'.
    dependencyInsight - Displays the insight into a specific dependency in root project 'projectReports'.
    api:dependencyInsight - Displays the insight into a specific dependency in project ':api'.
    webapp:dependencyInsight - Displays the insight into a specific dependency in project ':webapp'.
    dependentComponents - Displays the dependent components of components in root project 'projectReports'. [incubating]
    api:dependentComponents - Displays the dependent components of components in project ':api'. [incubating]
    webapp:dependentComponents - Displays the dependent components of components in project ':webapp'. [incubating]
    help - Displays a help message.
    api:help - Displays a help message.
    webapp:help - Displays a help message.
    model - Displays the configuration model of root project 'projectReports'. [incubating]
    api:model - Displays the configuration model of project ':api'. [incubating]
    webapp:model - Displays the configuration model of project ':webapp'. [incubating]
    projects - Displays the sub-projects of root project 'projectReports'.
    api:projects - Displays the sub-projects of project ':api'.
    webapp:projects - Displays the sub-projects of project ':webapp'.
    properties - Displays the properties of root project 'projectReports'.
    api:properties - Displays the properties of project ':api'.
    webapp:properties - Displays the properties of project ':webapp'.
    tasks - Displays the tasks runnable from root project 'projectReports' (some of the displayed tasks may belong to subprojects).
    api:tasks - Displays the tasks runnable from project ':api'.
    webapp:tasks - Displays the tasks runnable from project ':webapp'.

    Other tasks
    -----------
    api:compile - Compiles the source files
    webapp:compile - Compiles the source files
    docs - Builds the documentation

### 4.7.3. Show task usage details

Running `gradle help --task someTask` gives you detailed information about a specific task or multiple tasks matching the given task name in your multi-project build. Below is an example of this detailed information:

Example 4.13. Obtaining detailed help for tasks

Output of `gradle -q help --task libs`

    > gradle -q help --task libs
    Detailed task information for libs

    Paths
         :api:libs
         :webapp:libs

    Type
         Task (org.gradle.api.Task)

    Description
         Builds the JAR

    Group
         build

This information includes the full task path, the task type, possible commandline options and the description of the given task.

### 4.7.4. Listing project dependencies

Running `gradle dependencies` gives you a list of the dependencies of the selected project, broken down by configuration. For each configuration, the direct and transitive dependencies of that configuration are shown in a tree. Below is an example of this report:

Example 4.14. Obtaining information about dependencies

Output of `gradle -q dependencies api:dependencies webapp:dependencies`

    > gradle -q dependencies api:dependencies webapp:dependencies

    ------------------------------------------------------------
    Root project
    ------------------------------------------------------------

    No configurations

    ------------------------------------------------------------
    Project :api - The shared API for the application
    ------------------------------------------------------------

    compile
    \--- org.codehaus.groovy:groovy-all:2.4.7

    testCompile
    \--- junit:junit:4.12
         \--- org.hamcrest:hamcrest-core:1.3

    ------------------------------------------------------------
    Project :webapp - The Web application implementation
    ------------------------------------------------------------

    compile
    +--- project :api
    |    \--- org.codehaus.groovy:groovy-all:2.4.7
    \--- commons-io:commons-io:1.2

    testCompile
    No dependencies

Since a dependency report can get large, it can be useful to restrict the report to a particular configuration. This is achieved with the optional `--configuration` parameter:

Example 4.15. Filtering dependency report by configuration

Output of `gradle -q api:dependencies --configuration testCompile`

    > gradle -q api:dependencies --configuration testCompile

    ------------------------------------------------------------
    Project :api - The shared API for the application
    ------------------------------------------------------------

    testCompile
    \--- junit:junit:4.12
         \--- org.hamcrest:hamcrest-core:1.3

### 4.7.5. Listing project buildscript dependencies

Running `gradle buildEnvironment` visualises the buildscript dependencies of the selected project, similarly to how `gradle dependencies` visualises the dependencies of the software being built.

### 4.7.6. Getting the insight into a particular dependency

Running `gradle dependencyInsight` gives you an insight into a particular dependency (or dependencies) that match specified input. Below is an example of this report:

Example 4.16. Getting the insight into a particular dependency

Output of `gradle -q webapp:dependencyInsight --dependency groovy --configuration compile`

    > gradle -q webapp:dependencyInsight --dependency groovy --configuration compile
    org.codehaus.groovy:groovy-all:2.4.7
    \--- project :api
         \--- compile

This task is extremely useful for investigating the dependency resolution, finding out where certain dependencies are coming from and why certain versions are selected. For more information please see the `DependencyInsightReportTask` class in the API documentation.

The built-in dependencyInsight task is a part of the 'Help' tasks group. The task needs to be configured with the dependency and the configuration. The report looks for the dependencies that match the specified dependency spec in the specified configuration. If Java related plugins are applied, the dependencyInsight task is pre-configured with the 'compile' configuration because typically it's the compile dependencies we are interested in. You should specify the dependency you are interested in via the command line '--dependency' option. If you don't like the defaults you may select the configuration via the '--configuration' option. For more information see the `DependencyInsightReportTask` class in the API documentation.

### 4.7.7. Listing project properties

Running `gradle properties` gives you a list of the properties of the selected project. This is a snippet from the output:

Example 4.17. Information about properties

Output of `gradle -q api:properties`

    > gradle -q api:properties

    ------------------------------------------------------------
    Project :api - The shared API for the application
    ------------------------------------------------------------

    allprojects: [project ':api']
    ant: org.gradle.api.internal.project.DefaultAntBuilder@12345
    antBuilderFactory: org.gradle.api.internal.project.DefaultAntBuilderFactory@12345
    artifacts: org.gradle.api.internal.artifacts.dsl.DefaultArtifactHandler_Decorated@12345
    asDynamicObject: DynamicObject for project ':api'
    baseClassLoaderScope: org.gradle.api.internal.initialization.DefaultClassLoaderScope@12345
    buildDir: /home/user/gradle/samples/userguide/tutorial/projectReports/api/build
    buildFile: /home/user/gradle/samples/userguide/tutorial/projectReports/api/build.gradle

### 4.7.8. Profiling a build

The `--profile` command line option will record some useful timing information while your build is running and write a report to the `build/reports/profile` directory. The report will be named using the time when the build was run.

This report lists summary times and details for both the configuration phase and task execution. The times for configuration and task execution are sorted with the most expensive operations first. The task execution results also indicate if any tasks were skipped (and the reason) or if tasks that were not skipped did no work.

Builds which utilize a buildSrc directory will generate a second profile report for buildSrc in the `buildSrc/build` directory.

## 4.8. Dry Run

Sometimes you are interested in which tasks are executed in which order for a given set of tasks specified on the command line, but you don't want the tasks to be executed. You can use the `-m` option for this. For example, if you run “`gradle -m clean compile`”, you'll see all the tasks that would be executed as part of the `clean` and `compile` tasks. This is complementary to the `tasks` task, which shows you the tasks which are available for execution.

## 4.9. Summary

In this chapter, you have seen some of the things you can do with Gradle from the command-line. You can find out more about the gradle command in Appendix D, Gradle Command Line.