Java 11 shebang example in Docker
In Java 11, JEP 330 adds support to run single-file source code directly.
Terminal
# Before Java 11
$ javac Hello.java
$ java Hello
# Now Java 11
$ java Hello.java
This indirectly supports the Java single-file program to run as a script using Unix Shebang. For example, run below .sh
file will print Hello World!
.
run.sh
#!/opt/java/openjdk/bin/java --source 11
public class SheBang {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
P.S Make sure the !#
is pointed to the correct java
.
Test in Docker
Since I don’t have Linux on hands, so this example will test on Windows, using Docker image adoptopenjdk/openjdk11:alpine
.
This example runs a Java program as a shell script, using run.sh
file. Read comments for self-explanatory.
Windows
# This is Windows command prompt
# first run, it will take some time to download the image
# run alpine with openjdk11 installed, and start shell sh
> docker run -it adoptopenjdk/openjdk11:alpine sh
# done, enter the shell automatically
/ #
# make sure Java installed
/ # java -version
openjdk version "11.0.7" 2020-04-14
OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.7+10)
OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.7+10, mixed mode)
# find out where is java
/ # which java
/opt/java/openjdk/bin/java
/ # nano
sh: nano: not found
# we need an editor, apk install nano
/ # apk add nano
/ # nano run.sh
put this
run.sh
#!/opt/java/openjdk/bin/java --source 11
public class SheBang {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
Windows
# still inside container
# assign execute permission
/ # chmod +x run.sh
# run it, done.
/ # ./run.sh
Hello World!
# bye
/ # exit
References
About Author
Comments
Subscribe
0 Comments