Run Scala application on different process - scala

Question

Hi I want to create a program that starts another application on a new process:
object A{
def main(args: Array[String]) {
Process(????).run
println("new process has been created")
}
}
the application that should run on the new process:
object B{
def main(args: Array[String]) {
print("Hello world")
}
}
I know I can run a script using Process(script_string_to_run), but I don't know how to make it run another application..

Answer 1

Run Scala program from another Scala program
Scala Program
B.scala
object B {
def main(args: Array[String]): Unit = println("hello world")
}
Now execute the above program like this from another Scala program.
scala> import sys.process._
import sys.process._
scala> "scala B.scala" !!
warning: there was one feature warning; re-run with -feature for details
res1: String =
"hello world
"
Note that the file name of the file is same as the object name containing main method. This way scala would recognise the main class/object and execute the main method of the program. If the name of the file is not the name of the object containing the main method then It would not know what to execute.
! gives the exit status of the program after execution whereas !! gives the output of the program.
scala> import sys.process._
import sys.process._
scala> val status = "scala B.scala" !
warning: there was one feature warning; re-run with -feature for details
hello world
status: Int = 0
scala> val output = "scala B.scala" !!
warning: there was one feature warning; re-run with -feature for details
output: String =
"hello world
Scala Script
Test.sh
#!/usr/bin/env scala
object B{
def main(args: Array[String]) {
print("Hello world")
}
}
B.main(Array[String]())
Now Just run the B program using
"./Test.sh" !!
Command Line Activity
➜ cd demo
➜ demo ./Test.sh
zsh: permission denied: ./Test.sh
➜ demo chmod +rwx Test.sh
➜ demo ./Test.sh
Hello world%
➜ demo ./Test.sh
Hello world%
➜ demo scala
Welcome to Scala 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_45).
Type in expressions for evaluation. Or try :help.
scala> import sys.process._
import sys.process._
scala> "./Test.sh" !!
warning: there was one feature warning; re-run with -feature for details
res0: String =
"Hello world
"
scala> :q