I'm playing a bit around with a small JAVA gui for the command line mode of cloudcompare.
Therefore I'm using a short snippet like these:
var processBuilder = new ProcessBuilder();
try {
var process = processBuilder
.command("open", "-a", "CloudCompare.app", "-n",
"--args", "-NO_TIMESTAMP", "-C_EXPORT_FMT", "LAS",
"-O", "/Users/se/pcl_1.las",
"-O", "/Users/se/pcl_2.las",
"-MERGE_CLOUDS")
.start();
String error, line;
BufferedReader inputStream = new BufferedReader(new InputStreamReader(process.getInputStream()));
while ((line = inputStream.readLine()) != null) {
System.out.println("line = " + line);
}
BufferedReader errorStream = new BufferedReader(new InputStreamReader(process.getErrorStream()));
while ((error = errorStream.readLine()) != null) {
System.out.println("error = " + error);
}
var ret = process.waitFor();
System.out.printf("Program exited with code: %d", ret);
} catch (IOException | InterruptedException e) {
e.printStackTrace();
}
But if I run it on macOS the command line window opens, the process runs normal, but I can't grab any of the informations in it. There is an option to write log files from cloudcompare. That works - the log file shows that all cloud processing steps are done.
Does anybody knows, how to grab the command line output?
As mentioned here, the /usr/bin/open command is not an option to grab the stdinput stream.
I change the command to /Applications/CloudCompare.app/Contents/MacOS/CloudCompare and it works.
The next question is, how to grab the InputStream with a thread. I tried some stack overflow topics, but it doesn't work at the moment, to get the output stream in realtime. It is flushed at the end of the CloudCompare process.
I'm trying to manage my minecraft server through java but even though i can read outputs easily I can't manage to get commands or even text in:
ProcessBuilder builder = new ProcessBuilder(
"cmd.exe", "/c", "cd C:\\my\\path\\ && java -jar server.jar nogui");
builder.redirectErrorStream(true);
Process p;
p = builder.start();
this.p = p;
BufferedReader r = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line;
while (loop) {
line = r.readLine();
if (line == null) { break; }
System.out.println(line);
}
This works just fine but when I try to send commands it doesn't work at all:
OutputStream os = BotData.minecraftServer.getOutputStream();
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(os));
String stop = "stop";
try {
out.write(stop + "\n");
out.write("\n");
out.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I've tried with "Command:>>" + stop + "\n"
with or without / before stop etc.
Killing the process, forcibly or not, starting it in a thread I'd then stop...
I can get neither text nor commands to work.
document says commands from cmd should come with a leading /.
Try send /stop instead of stop.
Also mind, the line line = r.readLine(); may never return a null while the process is alive(by default).
OK found it, it is needed to use write() newline() then flush() to send anything to the console.
My second problem was a dead reference to my process.
destroying the process doesn't work, but the stop command does.
using / is useless, \n doesn't replace newline()
I have a webappliaction(developed in Jsp & Severlet) that execute the sh script and displays the output in browser only after executing the script but i want to print the output like how its executing in teriminal (one by one for eg ping command).So that user will have the experience like working in unix terminal. My script will run almost one minute(Script to start stop my WAS servers) so the user should not wait till one minute to see the final output . They should see the script started output once they start the process .please find my sample code below.
pb = new ProcessBuilder("/bin/sh",script);
pb.directory(new File(filePath));
p = pb.start();
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
while ((line = reader.readLine()) != null){
System.out.println(line);
out.println(line);
}
p.waitFor();
System.out.println ("exit: " + p.exitValue());
out.println("exit: " + p.exitValue());
p.destroy();
out.println("Script Executed");
Please anyone guide me.
Finally i got a solution for my problem, I just added out.flush() after out.println(line);So its flushing output to browser each time in while loop and its looks like unix terminal . Below code did the magic.
pb = new ProcessBuilder("/bin/sh",script);
pb.directory(new File(filePath));
p = pb.start();
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
while ((line = reader.readLine()) != null){
System.out.println(line);
out.println(line);
out.flush();
}
p.waitFor();
System.out.println ("exit: " + p.exitValue());
out.println("exit: " + p.exitValue());
p.destroy();
out.println("Script Executed");
Your problem is invisible here in the code example because it works just fine locally (e.g. for System.out). So logic implies that the problem must be somewhere in networking between client and server. Neither do you show how out is created (I guess it is some kind of socket-connected PrintStream) nor how the JSP reads it. What you want is some AJAX approach (XmlHttpRequest or similar) and probably you do not use it, but some "naïve", old-fashioned way. I am not a web developer, but your favourite search engine or some other people here might be able to help you with that part.
I have the following class file. This start a command prompt and print the responses. weird thing is after the first print i.e. dir the subsequent doesn't print. Please advice.
import java.io.*;
public class JavaApplication14 {
static Process p;
public static void main(String[] args) {
try {
String line;
p = Runtime.getRuntime().exec("cmd.exe");
OutputStream stdin = p.getOutputStream();
InputStream stderr = p.getErrorStream();
InputStream stdout = p.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(stdout));
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(stdin));
String input = "dir";
input += "\n";
writer.write(input);
writer.flush();
while ((line = reader.readLine()) != null) {
System.out.println("Stdout: " + line);
}
input = "cd..";
input += "\n";
writer.write(input);
writer.flush();
input = "dir";
input += "\n";
writer.write(input);
writer.close();
while ((line = reader.readLine()) != null) {
System.out.println("Stdout: " + line);
}
} catch (IOException ex) {
Logger.getLogger(JavaApplication14.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
Your (first) while() loop never terminates:
while ((line = reader.readLine()) != null) {
System.out.println("Stdout: " + line);
}
readLine() returns null when the stream is closed, but since your sub process is still running, the stream never gets closed.
To solve this, you can either move the reading part into a separate thread (which requires additional synchronization), or a simpler solution would be to see if a specific line contents is read, for example if the command line prompt was printed by cmd.exe:
while ( !(line = reader.readLine()).startsWith("C:\\") ) {
System.out.println("Stdout: " + line);
}
This should work for your particular use case, and might be sufficient to do some learning - for real applications, you might want to have a look into the Apache Commons Exec project.
You are trying to do fundamentally asynchronous work from just one thread, using synchronous I/O operations. Your approach is bound to fail.
Specifically, readLine() blocks until there is a full line to be read, or until the underlying stream is closed.
You'll have to write quite a bit more code, involving threads, to make this work. This is a pain point in Java.
You could also use the ProcessBuilder, especially its redirectOutput method with the argument value INHERIT, to make the subprocess inherit your main process's stdout. In this scenario you won't have the opportunity to analyze the subprocess's output in Java.
Process process = Runtime.getRuntime().exec("tasklist");
BufferedReader reader =
new BufferedReader(new InputStreamReader(process.getInputStream()));
process.waitFor();
There are many reasons that waitFor() doesn't return.
But it usually boils down to the fact that the executed command doesn't quit.
This, again, can have many reasons.
One common reason is that the process produces some output and you don't read from the appropriate streams. This means that the process is blocked as soon as the buffer is full and waits for your process to continue reading. Your process in turn waits for the other process to finish (which it won't because it waits for your process, ...). This is a classical deadlock situation.
You need to continually read from the processes input stream to ensure that it doesn't block.
There's a nice article that explains all the pitfalls of Runtime.exec() and shows ways around them called "When Runtime.exec() won't" (yes, the article is from 2000, but the content still applies!)
It appears you are not reading the output before waiting for it to finish. This is fine only if the output doesn't fill the buffer. If it does, it will wait until you read the output, catch-22.
Perhaps you have some errors which you are not reading. This would case the application to stop and waitFor to wait forever. A simple way around this is to re-direct the errors to the regular output.
ProcessBuilder pb = new ProcessBuilder("tasklist");
pb.redirectErrorStream(true);
Process process = pb.start();
BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line;
while ((line = reader.readLine()) != null)
System.out.println("tasklist: " + line);
process.waitFor();
Also from Java doc:
java.lang
Class Process
Because some native platforms only provide limited buffer size for standard input and
output streams, failure to promptly write the input stream or read the output stream of
the subprocess may cause the subprocess to block, and even deadlock.
Fail to clear the buffer of input stream (which pipes to the output stream of subprocess)
from Process may lead to a subprocess blocking.
Try this:
Process process = Runtime.getRuntime().exec("tasklist");
BufferedReader reader =
new BufferedReader(new InputStreamReader(process.getInputStream()));
while ((reader.readLine()) != null) {}
process.waitFor();
I would like to add something to the previous answers but since I don't have the rep to comment, I will just add an answer. This is directed towards android users which are programming in Java.
Per the post from RollingBoy, this code almost worked for me:
Process process = Runtime.getRuntime().exec("tasklist");
BufferedReader reader =
new BufferedReader(new InputStreamReader(process.getInputStream()));
while ((reader.readLine()) != null) {}
process.waitFor();
In my case, the waitFor() was not releasing because I was executing a statement with no return ("ip adddr flush eth0"). An easy way to fix this is to simply ensure you always return something in your statement. For me, that meant executing the following: "ip adddr flush eth0 && echo done". You can read the buffer all day, but if there is nothing ever returned, your thread will never release its wait.
Hope that helps someone!
There are several possibilities:
You haven't consumed all the output on the process's stdout.
You haven't consumed all the output on the process's stderr.
The process is waiting for input from you and you haven't provided it, or you haven't closed the process's stdin.
The process is spinning in a hard loop.
As others have mentioned you have to consume stderr and stdout.
Compared to the other answers, since Java 1.7 it is even more easy. You do not have to create threads yourself anymore to read stderr and stdout.
Just use the ProcessBuilder and use the methods redirectOutput in combination with either redirectError or redirectErrorStream.
String directory = "/working/dir";
File out = new File(...); // File to write stdout to
File err = new File(...); // File to write stderr to
ProcessBuilder builder = new ProcessBuilder();
builder.directory(new File(directory));
builder.command(command);
builder.redirectOutput(out); // Redirect stdout to file
if(out == err) {
builder.redirectErrorStream(true); // Combine stderr into stdout
} else {
builder.redirectError(err); // Redirect stderr to file
}
Process process = builder.start();
For the same reason you can also use inheritIO() to map Java console with external app console like:
ProcessBuilder pb = new ProcessBuilder(appPath, arguments);
pb.directory(new File(appFile.getParent()));
pb.inheritIO();
Process process = pb.start();
int success = process.waitFor();
You should try consume output and error in the same while
private void runCMD(String CMD) throws IOException, InterruptedException {
System.out.println("Standard output: " + CMD);
Process process = Runtime.getRuntime().exec(CMD);
// Get input streams
BufferedReader stdInput = new BufferedReader(new InputStreamReader(process.getInputStream()));
BufferedReader stdError = new BufferedReader(new InputStreamReader(process.getErrorStream()));
String line = "";
String newLineCharacter = System.getProperty("line.separator");
boolean isOutReady = false;
boolean isErrorReady = false;
boolean isProcessAlive = false;
boolean isErrorOut = true;
boolean isErrorError = true;
System.out.println("Read command ");
while (process.isAlive()) {
//Read the stdOut
do {
isOutReady = stdInput.ready();
//System.out.println("OUT READY " + isOutReady);
isErrorOut = true;
isErrorError = true;
if (isOutReady) {
line = stdInput.readLine();
isErrorOut = false;
System.out.println("=====================================================================================" + line + newLineCharacter);
}
isErrorReady = stdError.ready();
//System.out.println("ERROR READY " + isErrorReady);
if (isErrorReady) {
line = stdError.readLine();
isErrorError = false;
System.out.println("ERROR::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::" + line + newLineCharacter);
}
isProcessAlive = process.isAlive();
//System.out.println("Process Alive " + isProcessAlive);
if (!isProcessAlive) {
System.out.println(":::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: Process DIE " + line + newLineCharacter);
line = null;
isErrorError = false;
process.waitFor(1000, TimeUnit.MILLISECONDS);
}
} while (line != null);
//Nothing else to read, lets pause for a bit before trying again
System.out.println("PROCESS WAIT FOR");
process.waitFor(100, TimeUnit.MILLISECONDS);
}
System.out.println("Command finished");
}
I think I observed a similar problem: some processes started, seemed to run successfully but never completed. The function waitFor() was waiting forever except if I killed the process in Task Manager.
However, everything worked well in cases the length of the command line was 127 characters or shorter. If long file names are inevitable you may want to use environmental variables, which may allow you keeping the command line string short. You can generate a batch file (using FileWriter) in which you set your environmental variables before calling the program you actually want to run.
The content of such a batch could look like:
set INPUTFILE="C:\Directory 0\Subdirectory 1\AnyFileName"
set OUTPUTFILE="C:\Directory 2\Subdirectory 3\AnotherFileName"
set MYPROG="C:\Directory 4\Subdirectory 5\ExecutableFileName.exe"
%MYPROG% %INPUTFILE% %OUTPUTFILE%
Last step is running this batch file using Runtime.
Here is a method that works for me.
NOTE: There is some code within this method that may not apply to you, so try and ignore it. For example "logStandardOut(...), git-bash, etc".
private String exeShellCommand(String doCommand, String inDir, boolean ignoreErrors) {
logStandardOut("> %s", doCommand);
ProcessBuilder builder = new ProcessBuilder();
StringBuilder stdOut = new StringBuilder();
StringBuilder stdErr = new StringBuilder();
boolean isWindows = System.getProperty("os.name").toLowerCase().startsWith("windows");
if (isWindows) {
String gitBashPathForWindows = "C:\\Program Files\\Git\\bin\\bash";
builder.command(gitBashPathForWindows, "-c", doCommand);
} else {
builder.command("bash", "-c", doCommand);
}
//Do we need to change dirs?
if (inDir != null) {
builder.directory(new File(inDir));
}
//Execute it
Process process = null;
BufferedReader brStdOut;
BufferedReader brStdErr;
try {
//Start the command line process
process = builder.start();
//This hangs on a large file
// https://stackoverflow.com/questions/5483830/process-waitfor-never-returns
//exitCode = process.waitFor();
//This will have both StdIn and StdErr
brStdOut = new BufferedReader(new InputStreamReader(process.getInputStream()));
brStdErr = new BufferedReader(new InputStreamReader(process.getErrorStream()));
//Get the process output
String line = null;
String newLineCharacter = System.getProperty("line.separator");
while (process.isAlive()) {
//Read the stdOut
while ((line = brStdOut.readLine()) != null) {
stdOut.append(line + newLineCharacter);
}
//Read the stdErr
while ((line = brStdErr.readLine()) != null) {
stdErr.append(line + newLineCharacter);
}
//Nothing else to read, lets pause for a bit before trying again
process.waitFor(100, TimeUnit.MILLISECONDS);
}
//Read anything left, after the process exited
while ((line = brStdOut.readLine()) != null) {
stdOut.append(line + newLineCharacter);
}
//Read anything left, after the process exited
while ((line = brStdErr.readLine()) != null) {
stdErr.append(line + newLineCharacter);
}
//cleanup
if (brStdOut != null) {
brStdOut.close();
}
if (brStdErr != null) {
brStdOut.close();
}
//Log non-zero exit values
if (!ignoreErrors && process.exitValue() != 0) {
String exMsg = String.format("%s%nprocess.exitValue=%s", stdErr, process.exitValue());
throw new ExecuteCommandException(exMsg);
}
} catch (ExecuteCommandException e) {
throw e;
} catch (Exception e) {
throw new ExecuteCommandException(stdErr.toString(), e);
} finally {
//Log the results
logStandardOut(stdOut.toString());
logStandardError(stdErr.toString());
}
return stdOut.toString();
}
Asynchronous reading of stream combined with avoiding Wait with a timeout will solve the problem.
You can find a page explaining this here http://simplebasics.net/.net/process-waitforexit-with-a-timeout-will-not-be-able-to-collect-the-output-message/
public static void main(String[] args) throws PyException, IOException, InterruptedException
these should be the exceptions thrown