如何在 shell 脚本中检查 JAVA 程序是否成功执行？

Question

I am running java program from shell script. I need to execute next step in same shell script based on if any exception occur in java program or it ran successful.I am aware that java doesn't run anything. How can we do it in shell script? I know that we can print some string in log and grep it to check the status. is there any better way to do this? It would be good even if I can get some elegant way to do it using grep.

Answer 1

If a Java program was terminated because of an exception, the JVM will exit with an error status 1 , instead of the usual success status 0 . For example, this program exits because of a NullPointerException:

shell$ cat Throw.java
public class Throw {
    public static void main(String[] args) {
        String s = null;
        System.out.println(s.length());
    }
}
shell$ java Throw 2>/dev/null; echo $?
1

You can use the exit status in a shell if-statement for example. This will print boo :

if java Throw 2>/dev/null ; then
   echo woo
else
   echo boo
fi

If you want to set an exit code other than 1, use the System.exit(int status) function.