Question

I’m on a Mac OS X 10.8.2

I have a simple bash script executing a jar file (a simple hello world gui program with a window)

#!/bin/sh

if ls /Applications/javahello.jar >& /dev/null ; then
    echo "File exists."
     java -jar /Applications/javahello.jar
     exit 0 
else
     echo "File doesn't exist."
     exit 1
fi

The problem is that the script executes the jar, a window pops up and the terminal window stays “occupied” with a File Exists message. it never finishes its execution. …until I manually terminate the java program more precisely

I need to be able to execute the java program in this bash script in such a way that the script exits without waiting for the java program to finish running.

This would occur at the end of a installer package that copies the jar file into /Applications/ folder … as is, the installer never finishes and is obviously waiting for shell script to finish its execution.

Answer 1

Just put the java process in the background with &.

#!/bin/sh
if ls /Applications/javahello.jar >& /dev/null ; then
  echo "File exists."
  java -jar /Applications/javahello.jar &
  exit 0 
else
  echo "File doesn't exist."
  exit 1
fi

Also, you don’t need ls to tell if a file exists:

#!/bin/sh
if [ -f /Applications/javahello.jar ]; then
  echo "File exists."
  java -jar /Applications/javahello.jar &
  exit 0 
else
  echo "File doesn't exist."
  exit 1
fi

Also also, since you’re using the filename twice, if you edit the script to change the filename or make a copy to run a different jar file or whatever, you might make a typo where the two filenames differ. A shell parameter will fix that so it can’t happen:

#!/bin/sh
jar=/Applications/javahello.jar
if [ -f "$jar" ]; then
  echo "File exists."
  java -jar "$jar" &
  exit 0 
else
  echo "File doesn't exist."
  exit 1
fi