I try start .sh script with user input from txtfield.
Idea: user write parametre in txt fild. When push the button and script start with this parametre.
My code:
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt)
{
String valueURL;
valueURL = URLtxt.getText().toString();
ProcessBuilder processBuilder = new ProcessBuilder();
// -- Linux --
// Run a shell command
processBuilder.command("bash", "-c","nikto -h", valueURL,");
try {
Process process = processBuilder.start();
StringBuilder output = new StringBuilder();
BufferedReader reader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
String line;
while ((line = reader.readLine()) != null) {
output.append(line + "\n");
}
int exitVal = process.waitFor();
if (exitVal == 0)
{
this.hide();
ScanWS sws = new ScanWS() ;
sws.setVisible(true);
An event istener is triggered in UI thread, so the processing must be fast. Your listener implementation waits for an external process, it can freeze your ui. All the process triggering and caring logic must start in a separate Thread.
A process is quite an old construction and it has input/output issue. A process writes something during it's work into a buffer of it's output stream and when the buffer is all filled - the process hungs, waiting for the output stream to make some space.
So, both process.input and process.output processors also must work in separate threads.
Just found this post (and found the code which I'm also pasting below):
java runtime.getruntime() getting output from executing a command line program
My question is, how do I kill the process? It seems that the code blocks in the while loop. I've tried several options like using a boolean, running all the code in a separate thread and stuff like this, but without any success.
I just want to start an Android emulator and kill it whenever I want.
Runtime rt = Runtime.getRuntime();
String[] commands = {"emulator", "-avd", "jenkins",
"-scale", "96dpi", "-dpi-device", "100"};
Process proc = rt.exec(commands);
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);
}
Okay.
Use below code to get The Process ID of that current running thread or Process.
String processName =java.lang.management.ManagementFactory.getRuntimeMXBean().getName();
String ProcessID = processName.split("#")[0];//Process Id
Use that Process ID to kill that Process in your CPU.
I think for that purpose you may wish to write any other trigger or any condition in While loop.
I am calling a bash scrip script from Java.
The script does the following:
cat /home/user/Downloads/bigtextfile.txt | grep 'hello'
This particular command when run command line takes about 1 second to complete on the text file which is 150MB.
When calling the bash script via Java using the following call:
command = "sh /home/user/bashfiletocall"
p = Runtime.getRuntime().exec(command);
The time to complete takes so long I don't wait.
Am I doing something very wrong and if not can you explain the reason for the huge lack in performance?
NOTE: I was running it in Netbeans and this seems to be the problem .. when I ran the file command line it was quick. The performance between execution in netbeans and command line is huge.
Many thanks.
private String executeCommand(String command) {
StringBuilder output = new StringBuilder();
BufferedReader reader = null;
Process p;
try {
p = Runtime.getRuntime().exec(command);
p.waitFor();
reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = "";
while ((line = reader.readLine())!= null) {
output.append(line + "\n");
}
} catch (Exception e) {
e.printStackTrace();
}
return output.toString();
}
After starting your process you need start reading from the input stream. Otherwise the buffers are running full and p.waitFor() waits forever.
Javadoc of the Process class:
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, or even deadlock.
I currently start a shell script from my Java by code looking like this:
ProcessBuilder processBuilder = new ProcessBuilder();
processBuilder.directory("/directory/where/the/script/is/located/");
String[] command = new String[]{"sh", "myScript.sh"};
processBuilder.command(command);
Map<String, String> env = processBuilder.environment();
//tweak the environment with needed additions
env.put(...);
Process p = processBuilder.start();
stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));
// read the output from the command
String line;
while ((line = stdInput.readLine()) != null)
{
logger.fine(line);
}
p.waitFor();
int returnCode = p.exitValue();
// Return something according to the return code
return ...;
If I now want to start the script and not wait for it to end (and thus losing the ability to return according to return code), but still with being able to tweak the environment beforehand? how should I proceed?
Thank you
Just do the entire thing in a new thread.
Wrap the entire above code in a Runnable and start a Thread for it. Your main code can continue doing something else.
In the runnable once you get the result from the child process use some notify(or observer pattern) to notify interested parties.
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