Detect command line invocation of a sketch?

jeremydouglass

I have a sketch that I want to

1. launch and run from PDE / app
2. launch, run once, and quit from the command line

In order to do this I need to detect whether it was run from the command line!

Currently I can assume a command line invocation if there are args present.

However, I would like to detect command line invocation even if there are no args. Is that possible?

boolean exitWhenDone;

void setup() {
  // detect command line invocation if args present
  if (args != null) {
    // default command line behavior - run and quit
    exitWhenDone = true;
    // override default with command line argument
    for (String arg : args) {
      if ("noexit".equals(arg)) {
        exitWhenDone=false;
      }
    }
  }
}

void draw() {
  if (exitWhenDone) {
    exit();
  }
}

The sketch detects CL invocation with any throwaway placeholder arg, e.g.

processing-java --sketch=`pwd`/CLTest --run myarg

It doesn't work without, because args is null:

processing-java --sketch=`pwd`/CLTest --run

koogs

What operating system is this? 8)

jeremydouglass

Hah!

macOS 10.12.6 (Sierra)

$ echo $SHELL
/bin/bash
$ bash --version
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin16)
$ processing-java --help | head -2

Command line edition for Processing 0262 (Java Mode)

koogs

this works in linux ("null" when run with ctrl-r in pde, prints the arg if run with ./tmpArgs whatever)

void setup() {
  println(args == null ? "null" : args);
}

oh, that's what you currently have...

jeremydouglass

Great! I'm trying to have the sketch distinguish between:

1. ctrl-r in pde
2. run with ./tmpNoArgs -- no args

In other words "Was I run from the command line with no args, or from PDE?"

koogs

void setup() {
  println(args == null ? "null" : args);
  //println(System.getProperties());
  println(System.getProperty("sun.java.command"));
}

that last one looks promising

koogs

ah, ok, i was running an exported app vs the pde. the processing-java version does a different sun.java.command again (ie can distinguish the three cases)

(as an aside, the linux export creates an additional shell script containing the following:

#!/bin/sh

APPDIR=$(readlink -f "$0")
APPDIR=$(dirname "$APPDIR")
java -Djna.nosys=true -Djava.library.path="$APPDIR:$APPDIR/lib" -cp "$APPDIR:$APPDIR/lib/tmpArgs.jar:$APPDIR/lib/core.jar:$APPDIR/lib/jogl-all.jar:$APPDIR/lib/gluegen-rt.jar:$APPDIR/lib/jogl-all-natives-linux-amd64.jar:$APPDIR/lib/gluegen-rt-natives-linux-amd64.jar" tmpArgs "$@"

}

where tmpArgs is the sketch name)

jeremydouglass

Excellent -- System.getProperty("sun.java.command") looks like exactly what I needed. Many thanks, @koogs.

koogs

the name suggests that it's an oracle thing. but it's in both the pde and command line version (the former is using openjdk, the latter oracle)

jeremydouglass

So, it turns out that if a sketch was called from PDE it will have been passed the flag "--external" -- if from the command line, not. Documented here:

Parameters used by Processing when running via the PDE
"--external": set when the applet is being used by the PDE

• https://processing.github.io/processing-javadocs/core/processing/core/PApplet.html#main-java.lang.String:A-

Parsing System.getProperty("sun.java.command") for that flag will detect PDE.

This is a reliable way to distinguish between a sketch being run in PDE or the command line even without using command line arguments.

I'm not yet sure how this affects exported applications, however.

jeremydouglass

Here is a demo sketch that combines reliable no-argument detection with argument parsing:

/**
 * CommandLineDetect
 * 2017-09-21 Jeremy Douglass - Processing 3.3.6 
 * Was a sketch run from PDE, or from the command line?
 * If from the command line, what are its arguments and their values?
 * 
 * Invoke it:
 * 1. from the command line above the sketch folder, with no arguments:
 *     processing-java --sketch=`pwd`/CommandLineDetect --run
 * 2. ...or with arguments:
 *     processing-java --sketch=`pwd`/CommandLineDetect --run foo bar=baz lorem="ipsum dolor sit amet, consectetur adipiscing elit" etc 
 * 3. or form PDE
 *
 * The sketch relies on the --external flag to detect a PDE launch, as per:
 * - processing.github.io/processing-javadocs/core/processing/core/PApplet.html#main-java.lang.String:A-
 * 
 * The command line passes in a String[] of args. If you wish to arguments of the:
 *  -  form foo=bar
 *  -  lorem="ipsum dolor"
 * 
 * Related forum discussions:
 * -  forum.processing.org/two/discussion/23999/detect-command-line-invocation-of-a-sketch
 * -  forum.processing.org/two/discussion/23924/handling-command-line-arguments-in-a-sketch
 * -  forum.processing.org/two/discussion/6457/how-to-use-arguments-with-an-application-built-with-processing
 */

boolean PDE;
StringDict argDict = new StringDict();

void setup() {

  // get invocation string
  String cmd = System.getProperty("sun.java.command");
  // check if launched from PDE
  if (cmd.contains("--external")) {
    PDE=true;
  } else {
    PDE=false;
  }

  // if there are command line arguments, print them:
  println(args == null ? "null" : args);

  // load command line arguments, load them
  if (args != null) {
    for (String arg : args) {
      String[] entry = split(arg, "=");
      if (entry.length == 1) {
        argDict.set(entry[0], "");
      }
      if (entry.length == 2) {
        argDict.set(entry[0], entry[1]);
      }
    }
  }

  // set default if specific arg not present
  if (!argDict.hasKey("xyzzy")) {
    println("Setting default for xyzzy");
    // ...do something
  }

  // demonstrate using arguments
  for (String arg : argDict.keyArray()) {
    switch(arg) {
    case "foo":
      // key only arg
      println("mode:", arg);
      // ...do something
      break;
    case "bar":
      // key=value arg
      println("Setting", arg, "=", argDict.get(arg));
      // ...do something
      break;
    case "lorem":
      // parsed value
      String parsed = join(sort(argDict.get(arg).split(" ")), " ");
      println("Sorting", arg, "=", parsed);
      // ...do something
      break;
    }
  }
  exit();
}