Running command from java produces empty output

Question

I need to run the below comand using java but it is running fine in terminal as

svn list http://192.168.0.19/svn/cc/Branch/Jobs/tt/jobs/ --username prasadh --password prasadh2k > output.txt

But when running the same via process builder it is returning empty result.

My code:

    ProcessBuilder pb = new ProcessBuilder("cmd", "C:\\Users\\dev112\\output", "svn", "list", "http://192.168.0.19/svn/cadgraf/Branch/Jobs/T0003SATHYABAMAT/Completedjobs", "--username", "prasadh", "--password", "prasadh2k", ">", "output.txt");
    pb.redirectErrorStream(true);
    try {
        Process p = pb.start();
        new Thread(new InputConsumerforImageMagick.InputConsumer(p.getInputStream())).start();
        try {
            System.err.println("Exited with: " + p.getErrorStream());
        } catch (Exception ex) {
            Logger.getLogger(AddImage.class.getName()).log(Level.SEVERE, null, ex);
        }
    } catch (IOException ex) {
        Logger.getLogger(AddImage.class.getName()).log(Level.SEVERE, null, ex);
    }

did you mean to drop the `/c` from "cmd /C command to run" I suggest you try running the whole command on the command line with the `cmd` Most likely you are getting an error and since you are ignoring the error stream you can't see it. — Peter Lawrey, Jan 23 '15 at 08:11
No am trying to write the output in a text file but it is creating text file but not writing any value ino it. — Prasath Bala, Jan 23 '15 at 08:12
When i try like this "ProcessBuilder pb = new ProcessBuilder("cmd", "/C:\\Users\\dev112\\output", "svn", "list", "http://192.168.0.19/svn/cadgraf/Branch/Jobs/T0003SATHYABAMAT/Completedjobs", "--username", "prasadh", "--password", "prasadh2k", ">", "output.txt");" output file is not created — Prasath Bala, Jan 23 '15 at 08:15
@ Aaron Digulla: Again it is creating empty file only of 0 kb — Prasath Bala, Jan 23 '15 at 08:17
@PrasathBala: Sorry, that should have been `"cmd", "/c", "svn list ..."` — Aaron Digulla, Jan 23 '15 at 08:21
Check this answer [Running external command with output](https://stackoverflow.com/a/46312819/2110245) — Singhak, Sep 20 '17 at 03:34
Check this answer [Running processBuilder with output](https://stackoverflow.com/a/46312819/2110245) — Singhak, Sep 20 '17 at 03:36

fge · Answer 1 · 2015-01-23T09:31:24.687

0

Don't go through cmd. Just run the command directly:

final Path cwd = Paths.get("c:\\Users\\dev112\\output");
Files.createDirectories(cwd);
final Path outfile = cwd.resolve("output.txt");

final ProcessBuilder pb = new ProcessBuilder("svn", "list",
    "http://192.168.0.19/svn/cadgraf/Branch/Jobs/T0003SATHYABAMAT/Completedjobs",
    "--username", "prasadh", "--password", "prasadh2k");

pb.directory(cwd.toFile());
pb.redirectOutput(outfile.toFile());

final int retcode = pb.start().waitFor();

What is more, why do you get the process' standard output if you output to a file? Do one or the other, not both. If you output to a file then read the contents of that file after the command is executed.

The sample above outputs to a file; just open a stream to that file afterwards using Files.newInputStream(outfile) (well, that is, if retcode is 0; if it isn't, your command has ended with an error; which also means that you should redirect stderr somewhere, too)

edited Jan 23 '15 at 09:31

answered Jan 23 '15 at 08:17

fge

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Note: `redirectOutput()` is only available since Java 7. – Aaron Digulla Jan 23 '15 at 08:20
@AaronDigulla yes, but then so is `Path`. And this is 2015, right? :p – fge Jan 23 '15 at 08:21
final int retcode = pb.build().waitFor(); ---> am getting error in this line. I tried this too but same result – Prasath Bala Jan 23 '15 at 08:25
@PrasathBala yes, error from my part, I fixed it. It should have been .start(), not .build(). – fge Jan 23 '15 at 08:26
pb.redirectOutput(output.toFile()); ---> error near output.tofile – Prasath Bala Jan 23 '15 at 08:36
@fge - i changed the above line to pb.redirectOutput(outfile.toFile()); but the result throws error like "Caused by: java.io.IOException: CreateProcess error=2, The system cannot find the file specified" – Prasath Bala Jan 23 '15 at 08:39
And what file? The svn command or the output file? Does the parent directory exist? – fge Jan 23 '15 at 09:29

score 0 · Answer 2 · answered Jan 23 '15 at 08:19

I/O redirection doesn't work well with ProcessBuilder. You should either call cmd.exe with

new ProcessBuilder("cmd", "/c", "svn ... > output.txt");

(i.e. you have to call cmd with exactly two arguments) or you must redirect yourself, that is you need to start a background thread which reads stdout from the process and writes it to output.txt. In that case, you should use:

new ProcessBuilder("svn", "list", ...);

The former is brittle when you have spaces in arguments. So I suggest the latter even though the Java code is much more complex.

You should also have a look at Commons Exec which makes it much easier to deal with external processes.

Or with Java 7, you can use pb.redirectOutput();

"you need to start a background thread which reads stdout from the process and writes it to output.txt" <-- eh? `ProcessBuilder` has `.redirectOutput()`... — fge, Jan 23 '15 at 08:20

score -1 · Answer 3 · answered Jan 23 '15 at 09:08

-1

This works for me:

String command = "svn list http://192.168.0.19/svn/cc/Branch/Jobs/tt/jobs/ --username prasadh --password prasadh2k";
ProcessBuilder processBuilder = new ProcessBuilder(command.split());
processBuilder.redirectOutput(new File("C:/Users/dev112/output/", "output.txt"));
processBuilder.start();

answered Jan 23 '15 at 09:08

Adriaan Koster

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Error: java.io.IOException: Cannot run program "": CreateProcess error=87, The parameter is incorrect at java.lang.ProcessBuilder.start(ProcessBuilder.java:1047) at java.lang.ProcessBuilder.start(ProcessBuilder.java:1047) at org.archiveindexer.dao.RuntimeDemo.main(RuntimeDemo.java:33) Caused by: java.io.IOException: CreateProcess error=87, The parameter is incorrect at java.lang.ProcessImpl.create(Native Method) at java.lang.ProcessImpl.(ProcessImpl.java:385) at java.lang.ProcessImpl.start(ProcessImpl.java:136) at java.lang.ProcessBuilder.start(ProcessBuilder.java:1028) ... 1 more – Prasath Bala Jan 23 '15 at 09:20

Running command from java produces empty output

3 Answers3