[Ghoser777]

Okay, all I want to do is call a stupid little perl command from my java app, and it refuses to behave.

Code:
      Runtime r = Runtime.getRuntime();
      String hello = "perl -e \'open(INFO, \">>info.txt\");\'";
      Process p = r.exec(hello);
      p.waitFor();
      BufferedReader in2 = new BufferedReader(new InputStreamReader (p.getErrorStream()));
      String emsg="",output="";
      while ((emsg = in2.readLine()) != null)
            output += " "+emsg;
      p.destroy();
      return ouput;

That's my code, mius all the throws clause and such. The returned output (the error message) is: "Can't find string terminator "'" anywhere before EOF at -e line 1." And yet if I return the variable hello instead, print that out, and then run it manually, it works fine. Does anyone know what's up? (I've tried it with ' and \', it doesn't make a difference)

Thanks,
F-bacher

[eyadams]

Two problems:

1. Runtime.exec(String) attempts to parse the parameter in the command to be run and it's arguments; it is performing additional escapes on your "-e" parameter. Do this instead:

> String[] hello = {"perl", "-e \"open(INFO, '>>info.txt');\""};
> Process p = r.exec(hello);

You should get the desired results.

2. Make output a StringBuffer instead of a String, and do this:

> while ((emsg = in2.readLine()) != null)
> output.append(emsg);

The code as you wrote it is inefficient - a new String object gets created for every line read from in2.readLine(). Switching to a StringBuffer will yield measurable improvements in speed and memory usage, especially if the output from the perl script is many lines long.

Erik