Running external script from Java application on OS X

Question

I'm having real issues getting an external script to run from my Java application on OS X 10.8. It works on Windows, so not sure what I'm doing wrong for OS X.

What works (Windows):

String[] commands = {
 "\"" + _appDataDir + "\\Temp\\Workers\\" + _batchName + "\"", 
 "\"" + _appDataDir + "\\Temp\\frame%d.jpg\"", 
 "\"" + _fileName + "\""};
proc = rt.exec(commands);

So I have the following for OS X:

String[] commands = {
 _appDataDir + "/Temp/Workers/" + _batchName,
_appDataDir + "/Temp/Workers/mac-ffmpeg", 
_appDataDir + "/Temp/frame%d.jpg", 
"\"" + _fileName + "\""};
proc = rt.exec(commands);

This works when there are no spaces in the filename, but fails when there are spaces with a "java.io.IOException: Bad file descriptor" error.

At the moment, I've changed all the paths to have no spaces as an easy fix, but I don't have control over the fileName string as this is selected by the user from a save dialog. I've tried with and without double quotes around fileName but neither make any difference.

I also tried ProcessBuilder as below (both with and without the "/bin/bash/, -c" bits):

ProcessBuilder proc2 = new ProcessBuilder(
 "/bin/bash",
"-c",
_appDataDir + "/Temp/Workers/" + _batchName,
_appDataDir + "/Temp/Workers/mac-ffmpeg",
_appDataDir + "/Temp/frame%d.jpg",
"\"" + _fileName + "\""
);
proc = proc2.start();

but this gives the same error. As far as I can tell I'm doing everything that's being suggested in other similar questions, but nothing is working. Any ideas would be appreciated!

Answer 1

You don't need the quotes around "\"" + _fileName + "\"", just a plain _fileName would work here. When you provide an array to Runtime.exec (or to ProcessBuilder) you've already split your command up into "words" - if you add the quotes you're telling it to look for a file whose name is actually double-quote + _fileName + double-quote rather than just _fileName.

The real problem is likely to lie within the _batchName program, which presumably is a shell script that does the real work by calling other programs. Within that script you will receive the mac-ffmpeg, frame%d.jpg and _fileName arguments as 1ドル, 2ドル and 3ドル, and you need to make sure that they are properly quoted within the script, e.g. if the script currently says something like

processFile 3ドル

then you need to change it to say

processFile "3ドル"

if it is to cope with file names that contain spaces. Or if it is set up to handle multiple files at once:

processFiles $*

then you need to replace that with

processFiles "$@"

• aritchie: That's great, thanks! Using quotes in the script itself has done the trick. What threw me here was that when I tried running the script and passing the arguments (with double quotes) from Terminal it worked fine, so I had assumed the issue lay with the Java code rather than the script.