Java Shell Command not Running from Current Directory

Question

In this question it shows that when you run a shell command from Java, it runs from the current directory. When I run the command javac Program.java from my program, it shows the error (from the standard error stream):

javac: file not found: Program.java
Usage: javac <options> <source files>
use -help for a list of possible options

However, when I run the same exact command from the actual Terminal, it works fine and saves the .class file in the default directory. This is the code:

Runtime rt = Runtime.getRuntime();
String command = "javac Program.java";
Process proc = rt.exec(command);

BufferedReader stdInput = new BufferedReader(new 
     InputStreamReader(proc.getInputStream()));

BufferedReader stdError = new BufferedReader(new 
     InputStreamReader(proc.getErrorStream()));

// read the output from the command
System.out.println("Here is the standard output of the command:\n");
String s = null;
while ((s = stdInput.readLine()) != null) {
    System.out.println(s);
}
// read any errors from the attempted command
System.out.println("Here is the standard error of the command (if any):\n");
while ((s = stdError.readLine()) != null) {
    System.out.println(s);
}
proc.waitFor();

Any ideas why it works when I type it in the actual Terminal, but not when I run it from my program? I am running a Max OS X Mountain Lion (10.6)

Thanks

Then try `javac src/Program.java` from your project directory. — , Jun 25 '15 at 00:37
@saka1029 That produced no errors, but it does not create a .class file in the default directory — APCoding, Jun 25 '15 at 00:40
However it does in `Volumes/Peter's Hardrive/Eclipse Programs/APC/src` — APCoding, Jun 25 '15 at 00:41
If you want to create it in the current directory, try `javac -d . src/Program.java`. If you want to create it in `bin` directory like Eclipse do so, try `javac -d bin src/Program.java`. — , Jun 25 '15 at 00:46
When I export the program into a .jar and run it in the desktop with `Program.java` also in the desktop, it produced the file not found error — APCoding, Jun 25 '15 at 00:56
As long as I remove the `src/` thing in the javac command, it works fine! Thanks for everyone's help! — APCoding, Jun 25 '15 at 00:59
Use `ProcessBuilder`, among a bunch of other useful methods, you can set the work `directory` in which the process is executed — MadProgrammer, Jun 25 '15 at 01:01
Posted all the collected knowledge (mostly from saka1029) into an answer — APCoding, Jun 25 '15 at 01:06
Need to wait 2 days until I can set my post to the correct answer — APCoding, Jun 25 '15 at 01:08
For [example](http://stackoverflow.com/questions/15218892/running-a-java-program-from-another-java-program/15220419#15220419) and [example](http://stackoverflow.com/questions/28955020/compiling-and-executing-using-exec-in-java-fails-using-command-that-works-from-t/28955036#28955036) — MadProgrammer, Jun 25 '15 at 01:12

score 1 · Answer 1 · edited May 23 '17 at 11:58

1

Your program is probably being run from a different directory. Your IDE (such as Eclipse) is probably is running from one location, and knows the directory structure to access your program files.

The easiest, quickest solution is to just write the fully-qualified file path for Program.java.

The alternate is to find out what the current directory is. So, perhaps run pwd the same way you are running javac Program.java from within your program's code? Then you can see what directory your program is actually being run from. Once you know that, you can write the appropriate directory structure.

For example, if pwd reveals that you are actually 2 directories above where Program.java is, then you can put those directories in the command like this: javac ./dir1/dir2/Program.java.

To change the directory Eclipse runs from, see this question Set the execution directory in Eclipse?

edited May 23 '17 at 11:58

Community

1
1

answered Jun 25 '15 at 00:32

Rock Lee

9,146
10
55
88

How do I change the directory then? – APCoding Jun 25 '15 at 00:33
Also, since it said in the link I had in my question that the command is run from the current Terminal directory, why does it run from the program directory? – APCoding Jun 25 '15 at 00:34
When I typed `pwd` it produced `/Volumes/Peter's Hardrive/Eclipse Programs/APC` – APCoding Jun 25 '15 at 00:36
Which is correct, so how can I change the directory inside the program? – APCoding Jun 25 '15 at 00:36
Thanks, but it has seemed that saka1029 has solved the problem, as you can see in the comments below my question – APCoding Jun 25 '15 at 00:57

long · Answer 2 · 2015-06-25T00:38:43.880

1

You can try to print the path in your programm ,use new File(".").getAbsolutePath() ,if you are in a ide ,the path may be in the root of the project rather than in the path of the current java file

edited Jun 25 '15 at 00:38

answered Jun 25 '15 at 00:35

long

59
6

Did that, produced `/Volumes/Peter's Hardrive/Eclipse Programs/APC` – APCoding Jun 25 '15 at 00:37
Running the command "pwd" also helps diagnose this; it'll run Unix present working directory wherever it's put itself. – Dean J Jun 25 '15 at 03:15

score 1 · Accepted Answer · answered Jun 25 '15 at 01:05

The reason my code was not working was because I was running it in Eclipse IDE, and that messes up the directory the program is running from. To fix that program, I changed the command to javac -d . src/Program.java. If I export the program into a .jar file and run it in the desktop, my original command will do just fine.

Thanks to saka1029 for helping me!

Java Shell Command not Running from Current Directory

3 Answers3