Running .jar Files in Ubuntu: A Comprehensive Guide
Are you new to Ubuntu and looking to execute Java applications? Running a .jar file in Ubuntu is a straightforward process, but it’s essential to understand the steps involved to ensure a smooth experience. In this guide, I’ll walk you through the process, covering everything from installation to execution.
Understanding .jar Files
.jar files are Java Archive files, containing compiled Java code, resources, and metadata. They are self-contained and can be executed on any platform with a Java Runtime Environment (JRE) installed.
Checking Java Installation
Before you can run a .jar file, you need to ensure that Java is installed on your Ubuntu system. To check if Java is installed, open a terminal and type:
java -versionIf Java is installed, you’ll see the version information. If not, you’ll need to install it. Ubuntu comes with OpenJDK, so you can install it using the following command:
sudo apt updatesudo apt install openjdk-8-jdkLocating the .jar File
Once Java is installed, locate the .jar file you want to run. You can use the ‘find’ command to search for the file:
find / -name "yourfile.jar"Replace “yourfile.jar” with the actual name of your .jar file. This command will search your entire system for the file. If you know the directory where the file is located, you can navigate to that directory using the ‘cd’ command.
Running the .jar File
With the .jar file located, you can now run it using the following command:
java -jar yourfile.jarReplace “yourfile.jar” with the actual name of your .jar file. If the file is located in a directory, you can also specify the directory path:
java -jar /path/to/yourfile.jarRunning .jar Files with Arguments
Some .jar files require arguments to run correctly. To pass arguments, you can add them after the -jar flag:
java -jar yourfile.jar arg1 arg2 arg3Replace “arg1”, “arg2”, and “arg3” with the actual arguments required by your .jar file.
Running .jar Files as a Service
For long-running .jar files, you might want to run them as a service. This can be done using the ‘systemd’ service manager. First, create a new service file in the /etc/systemd/system directory:
sudo nano /etc/systemd/system/yourfile.serviceThen, add the following content to the file:
[Unit]Description=Your File Service[Service]ExecStart=/path/to/java -jar yourfile.jarWorkingDirectory=/path/to/yourfileStandardOutput=inheritStandardError=inherit[Install]WantedBy=multi-user.targetReplace “/path/to/java” with the path to your Java executable and “/path/to/yourfile” with the directory containing your .jar file. Save and close the file.
Enable and start the service using the following commands:
sudo systemctl enable yourfile.servicesudo systemctl start yourfile.serviceRunning .jar Files with Different Java Versions
Ubuntu comes with multiple Java versions, and you might want to run a .jar file with a specific version. To do this, use the ‘update-alternatives’ command:
sudo update-alternatives --config javaSelect the Java version you want to use and press Enter. Then, run your .jar file as described earlier.
Running .jar Files with Different Java Versions (Continued)
Here’s a table showing the default Java versions in Ubuntu and their corresponding package names:
| Ubuntu Version | Default Java Version | Package Name |
|---|---|---|
| Ubuntu 18.04 LTS
|
