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A Better Shell Script Wrapper for JAR Files

To run a JAR file, usually you would do:

$ java -jar /path/to/jar

It’s a bit long to type, so some people (me included) would wrap it in a shell script:

run-jar.sh 
#!/usr/bin/bash
java -jar /path/to/jar

This way, you only have to type ./run-jar.sh, or run-jar.sh if you have the script somewhere in your shell’s PATH.

A problem with this approach is that you now have two files, the shell script and the JAR file. If you move or delete the JAR file, the script breaks. A better way to do this is to “include” the JAR file directly in the shell script.

First, we’ll change run-jar.sh’s shebang (#!) line from #!/usr/bin/bash to #!/usr/bin/java. This tells the shell to run the script using java -jar instead of the usual bash or sh:

$ echo '#!/usr/bin/java -jar' > run-jar.sh

Then, we’ll append the entire JAR file to the script:

$ cat /path/to/jar >> run-jar.sh

Finally, all we have to do is set the script file permission to executable:

$ chmod +x run-jar.sh

This way, everything you need to run the program is in a single file, making it simpler to manage.

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