JBang Cheatsheet (2023)

Here is my JBang cheatsheet which can help as a reference to code self-contained source-only Java programs with unmatched ease. If you are new to JBang we recommend checking this article: JBang: Create Java scripts like a pro

jbang cheatsheet for developers

Installation / Update

Install JBang on Linux

curl -Ls https://sh.jbang.dev | bash -s - app setup

How to upgrade JBang

jbang version --update

Run JBang Scripts

How to execute a JBang Script

jbang example.java

Run a Java class in a JAR file with JBang

jbang jgroups-4.2.15.Final.jar --main=org.jgroups.tests.McastReceiverTest

Run a Java class using Maven GAV coordinates

jbang org.jgroups:jgroups:5.1.9.Final --main=org.jgroups.tests.McastReceiverTest 

How to run a Java code snippet:

echo "hello world" | jbang -c 'lines().forEach(s->println(s.substring(6)))`

Create an executable JAR from a JBang script:

jbang export portable MyApp.java

Template Management

Create a JBang class  from a template

jbang init --template=hello helloworld.java

List of available JBang templates

jbang template list

JBang Configuration

How to add Adding a dependency to your script:

//DEPS log4j:log4j:1.2.17

Adding a GitHub project as dependency (JBang will download the project, build it as use it as a dependency)

//DEPS https://github.com/DiUS/java-faker

Adding Managed Dependencies (BOM)

//DEPS io.quarkus:quarkus-bom:1.11.0.Final@pom
//DEPS io.quarkus:quarkus-resteasy
//DEPS io.quarkus:quarkus-smallrye-openapi

How to use Sources and Jars as external dependencies in isolation, without being built inside the project (requires jBang v0.109.0 or newer):

//DEPS myapp.jar 
//DEPS myclass.java

Using System properties in the comments

//DEPS org.openjfx:javafx-graphics:11.0.2:${os.detected.jfxname}

Using Environment variables in the comments

//DEPS org.openjfx:javafx-graphics:11.0.2:${env.jfxname}

How to pass the dependencies as command line argument to a Script:

jbang --deps org.matheclipse:matheclipse-core:2.0.0,org.matheclipse:matheclipse-io:2.0.0 test.java

Adding file resources

//FILES resource.properties
//FILES META-INF/resources/index.html=index.html

Adding a Manifest file:

//MANIFEST version=${version:unknown}

Setting Quarkus properties

//Q:CONFIG quarkus.datasource.db-kind=postgresql

Remote file expansion (JBang will download the remote file – tagged with % – and pass it as argument)

jbang CountWords.java %https://github.com/dwyl/english-words/raw/master/words.txt

Repository Configuration

Configures a well-known repository (mavencentral) and a custom Repository “acme”

//REPOS mavencentral,acme=https://maven.acme.local/maven

Java Sources

How to specify the location of Java Sources (they will be built inside the project)

//SOURCES nested/*.java
//SOURCES othernested/*.java

You can also pass the sources (and resources) location from the command line:

jbang --sources src/main/java --files src/main/resources script.java

JDK configuration

Setting JDK in your code

//JAVA 11 will force use of Java 11.
//JAVA 13+ will require at least java 13. Java 13 or higher will be used.

How to install a JDK

jbang jdk install 17

How to install a JDK from a location on your machine:

jbang jdk install 17 `sdk home java`

Uninstall a JDK

jbang jdk uninstall 14

List available JDK

jbang jdk list

Setting default JDK

jbang jdk default 12

Debugging and JDK Settings

Debugging a Java class

jbang --debug helloworld.java

Setting java and javac options

//JAVAC_OPTIONS -source 11
//JAVA_OPTIONS -Xms128m -Xmx512m


Install an app from the Catalog

jbang app install CamelJBang@apache/camel

List of available apps

jbang app list


With this JBang cheatsheet, you now have access to a concise and well-structured guide that covers the essential commands, syntax, and functionalities of jbang. Whether you are a developer, a student, or simply curious about this powerful Java-based scripting tool, this cheatsheet will empower you to streamline your scripting workflow, automate tasks, and boost productivity.