Execing Processes in Scala

Here’s the translation of the Go code to Scala, with explanations adapted for Scala and formatted in Markdown suitable for Hugo:

Our example demonstrates how to replace the current process with another one in Scala. This is similar to the classic exec function in Unix-like operating systems.

import scala.sys.process._
import java.io.File

object ExecingProcesses {
  def main(args: Array[String]): Unit = {
    // For our example we'll exec `ls`. We'll use `which` to find the absolute path
    // to the binary we want to execute.
    val binary = Process("which ls").!!.trim

    // We'll give `ls` a few common arguments. Note that the first argument should
    // be the program name.
    val args = List("ls", "-a", "-l", "-h")

    // We also need to provide the current environment variables.
    val env = sys.env

    // Here's the actual process creation and execution. If this call is
    // successful, the execution of our process will end here and be replaced
    // by the `ls -a -l -h` process. If there is an error, an exception will be thrown.
    try {
      val process = Process(binary +: args, new File("."), env.toSeq: _*)
      sys.exit(process.!)
    } catch {
      case e: Exception => println(s"Error executing process: ${e.getMessage}")
    }
  }
}

When we run our program, it is replaced by ls:

$ scala ExecingProcesses.scala
total 16
drwxr-xr-x  4 user 136B Oct 3 16:29 .
drwxr-xr-x 91 user 3.0K Oct 3 12:50 ..
-rw-r--r--  1 user 1.3K Oct 3 16:28 ExecingProcesses.scala

Note that Scala, being a JVM language, doesn’t offer a direct equivalent to Unix’s fork function. However, Scala’s concurrency model, based on Akka actors and futures, covers most use cases for parallel execution and process management.

In this example, we use Scala’s scala.sys.process package to execute external processes. The Process object allows us to create and run external processes, while sys.exit is used to terminate the current JVM with the exit code of the executed process.

Remember that this approach doesn’t truly replace the current process in the same way as the Unix exec system call. Instead, it runs the new process and exits the Scala program with the same exit code as the new process.