Develop Reference

process builder with redirecterrorstream hangs in readline

I would like to run a hidden script file that resides in the current location using process builder. with the following code
// System.out.println("line"+reader.readLine());
ProcessBuilder builder = new ProcessBuilder(shfile.getAbsolutePath());
builder.redirectErrorStream(true);
Process process = builder.start();
BufferedReader br = new BufferedReader(new InputStreamReader(process.getInputStream()));
String output = null;
System.out.println("out"); //===printing this
while (null != (output = br.readLine()))
{
System.out.println("in"); //not printing this
System.out.println(">>"+output);
}
int rs = process.waitFor();
but it hangs in the br.readline()..
but when I run the same script file using the following command in terminal
sh .script.sh
it executes and gives me the expected results
I looked into all the loops in the forum everyone asks to handle input stream and error stream in threads or do a redirect error stream. I have added a redirect error stream but still it hangs.
when i press ctrl+c it prints the initial lines of the output and exits.
Content of my script file
#!/bin/sh
cd /home/ats/cloudripper/lke_factory_asb_v2/lk_assets_factory_release/
sh ./LKE_run_Diablo.sh 0a0e0c3dc893
So how to handle this situation.

Process builder have special API to redirect child process input, output and error streams. See documentation
If you need both child and parent process to use same console you should use INHERIT mode redirection. An example:
public class ChildProcessOutputProxy {
public static void main(String[] args) {
ProcessBuilder builder = new ProcessBuilder("whoami");
builder.redirectOutput(Redirect.INHERIT);
builder.redirectErrorStream(true);
try {
var child = builder.start();
child.waitFor();
} catch (IOException e) {
System.err.println(e.getMessage());
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}

Command prompt is not closing after completing even after writing exit

I have following java code
public static void main(String a[]) {
String location = "C:\\Users\\test\\output\\testProject";
File dir = new File("C:\\Users\\test\\cmds");
ProcessBuilder pb = new ProcessBuilder("cmd.exe", "/C", "Start /wait","packageProject.bat",location);
pb.directory(dir);
Process p = null;
try {
p = pb.start();
p.waitFor();
}
catch (IOException e) {
e.printStackTrace();
}
catch(InterruptedException e) {
e.printStackTrace();
}
System.out.println("Folder created");
}
Batch file is
cd "C:\Users\test\output\test-master"
mvn clean install -DskipTests
exit
It is packaging file but not command prompt is not closing once process is complete.
Please suggest.

You should remove wrapper CMD.EXE and start, just call the batch file directly as:
String bat = new File(dir, "packageProject.bat").getAbsolutePath();
ProcessBuilder pb = new ProcessBuilder(bat , location);
pb.directory(dir);
Process p = pb.start();
p.waitFor();
If this process generates a lot of output you may run into a second problem if you don't consume error and output streams. You can do this in background threads, or simply send stdout/err to files by adding these calls before pb.start():
pb.redirectOutput(new File(location, "std.out"));
pb.redirectError(new File(location, "std.err"));

Running SoX from Processing/Java on Windows computer

This might be an easy one - but it's driving me nuts at this point. I'm trying to run SoX from Processing which on my mac computer is running smoothly and with no problems. I need to migrate the code to a windows 7 machine but can't get it to work for some reason. Talking to the terminal from processing works fine. I'm in the right folder (sketch data folder where SoX is also intalled) since I can run commands like "dir" etc. and get the right content printed - but as soon as I try to run sox.exe nothing happens (getting an exit value 1). Running sox.exe straight from the cmd terminal works fine. Here is a sample of what I'm trying to do:
void playBackYear (){
soxPlay = "cmd /c sox.exe year.wav -d";
println (soxPlay);
try {
File workingDir = new File(sketchPath("data"));
Process p=Runtime.getRuntime().exec(soxPlay, null, workingDir);
p.waitFor();
BufferedReader reader=new BufferedReader(
new InputStreamReader(p.getInputStream())
);
String line;
while ( (line = reader.readLine ()) != null)
{
println(line);
}
int exitVal = p.waitFor();
System.out.println("Exited with error code "+exitVal);
}
catch(IOException e1) {
System.err.println("Caught IOException: " + e1.getMessage());
System.out.println( "error 1" );
}
catch(InterruptedException e2) {
System.err.println("Caught IOException: " + e2.getMessage());
System.out.println( "error 2" );
}
}
So the questions is what am I doing wrong here?
Any help is appreciated.

I have written a small wrapper application that wraps sox binary in java. If you are interested in the full project, check it out on GitHub: sox java wrapper project
This is, how i have solved the problem:
private List<String> arguments = new ArrayList<String>();
// add sox arguments to this list above
public void execute() throws IOException {
File soxBinary = new File(soXBinaryPath);
if (!soxBinary.exists()) {
throw new FileNotFoundException("Sox binary is not available under the following path: " + soXBinaryPath);
}
arguments.add(0, soXBinaryPath);
logger.debug("Sox arguments: {}", arguments);
ProcessBuilder processBuilder = new ProcessBuilder(arguments);
processBuilder.redirectErrorStream(true);
Process process = null;
IOException errorDuringExecution = null;
try {
process = processBuilder.start();
BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line;
while ((line = reader.readLine()) != null) {
logger.debug(line);
}
} catch (IOException e) {
errorDuringExecution = e;
logger.error("Error while running Sox. {}", e.getMessage());
} finally {
arguments.clear();
if (process != null) {
process.destroy();
}
if (errorDuringExecution != null) {
throw errorDuringExecution;
}
}
}

How could I pass in commands into a terminal that is already running in java (linux)

I have been researching how to run a terminal command in java. I am doing this to make a program I can use to ssh into another pc (just as a project). How could I keep continuing putting commands in this terminal? If I run this I get a message to put in my password and if I do so it will print out what the messages the terminal spits out at the :
while((line = in.readLine()) != null){
System.out.println(line + "\n");
}
line, but a few seconds after that my program will stop working.
I currently have a GUI that is just a button and if I press the button it will run this code. Could someone help me to fix the issue of it stopping and give me information on how I could continue to put commands into the terminal? Thanks.
Process p = null;
String[] command = {"/bin/sh", "-c", "ssh 192.168.2.100"};
ProcessBuilder pb = new ProcessBuilder(command);
String line = null;
try {
term = pb.start();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
InputStream is = p.getInputStream();
BufferedReader in = new BufferedReader(new InputStreamReader(is));
try {
while((line = in.readLine()) != null){
System.out.println(line + "\n");
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
in.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

You can not pass the argument to live JVM, But there is way in which you can modify the some of the parameters which done using JMX, with this you can connect to live JVM and send the parameters. which will be taken the effect immediately.
Hope that helps

Java Runtime.exec() program won't output to file

I have a program that takes in a file as an input and produces an xml file as an output. When I call this from the command line it works perfectly. I try calling it from a Java program with the following code.
try
{
Process proc = Runtime.getRuntime().exec(c);
try
{
proc.waitFor();
}
catch(InterruptedException e)
{
System.out.println("Command failed");
}
}
catch(IOException e)
{
System.out.println("Command failed");
e.printStackTrace();
}
The program seems to be running fine, as it creates an xml file; however, the xml file is empty when I open it. I'm not encountering any exceptions in my Java program, so I'm baffled as to what the problem could be. Why would the command line program work fine normally, but then when called from Java not output anything to the file it created. I was thinking maybe it was some sort of permissions thing. I tried running the program as sudo (I'm using Linux) but to no avail. This problem doesn't seem to be anything I could find an answer to online. Hopefully somebody on here might be able to tell what's going on. :)

Get the output and error streams from your process and read them to see what is happening. That should tell you what's wrong with your command.
For example:
try {
final Process proc = Runtime.getRuntime().exec("dir");
try {
proc.waitFor();
} catch (final InterruptedException e) {
e.printStackTrace();
}
final BufferedReader outputReader = new BufferedReader(new InputStreamReader(proc
.getInputStream()));
final BufferedReader errorReader = new BufferedReader(new InputStreamReader(proc
.getErrorStream()));
String line;
while ((line = outputReader.readLine()) != null) {
System.out.println(line);
}
while ((line = errorReader.readLine()) != null) {
System.err.println(line);
}
} catch (final IOException e) {
e.printStackTrace();
}
If there is no output in either stream, then I would next examine the external program and the command being sent to execute it.

Did you try launching the process from outside java?

For me, I wrote a jar file that output a file and ran that from the command line in another java program. It turns out that there was a fundamental check in my jar file that I had forgotten about on the number of characters in an input string (my bad). If the count of the characters was smaller than 8 there was no output file. If the number of characters was greater than 8, the output file came out without any trouble using the following code:
String cmdStr = "java -jar somejar.jar /home/username/outputdir 000000001";
try
{
Runtime.getRuntime().exec(cmdStr);
Runtime.getRuntime().runFinalization();
Runtime.getRuntime().freeMemory();
log.info("Done");
}
catch (IOException e)
{
log.error(System.err);
}
Not sure if I really need everything here but, hey, it works. Note: no waitFor seems to be necessary in my case.

process input (actually output of the process!) and error streams has to be handled before waiting for the process termination.
This should work better
try
{
Process proc = Runtime.getRuntime().exec("anycomand");
BufferedReader outSt = new BufferedReader(new InputStreamReader(proc.getInputStream()));
BufferedReader errSt = new BufferedReader(new InputStreamReader(proc.getErrorStream()));
String line;
while ((line = outSt.readLine()) != null)
{
System.out.println(line);
}
while ((line = errSt.readLine()) != null)
{
System.err.println(line);
}
proc.waitFor();
}
catch (final IOException e)
{
e.printStackTrace();
}
but to understand better how Runtime exec works it is worth reading
the classic article
When Runtime.exec() won't
which provide useful sample code (better than the one above!)