Develop Reference

Redirecting the output of a process into the input of another process using ProcessBuilder in Java

I have two processes defined by processBuilders:
ProcessBuilder pb1 = new ProcessBuilder (...)
ProcessBuilder pb2 = new ProcessBuilder (...)
I want the output of pb1 to be the input to pb2.
I found in the documentation that I can make the input of pb2 to be read from another process by using pipe:
pb2.redirectInput(Redirect.PIPE);
However, how can I specify that I want this pipe to read from the output of pb1?

static ProcessBuilder.Redirect INHERIT Indicates that subprocess I/O
source or destination will be the same as those of the current
process.
static ProcessBuilder.Redirect PIPE Indicates that subprocess I/O
will be connected to the current Java process over a pipe.
So I don't think one of these will help you redirecting the output of one process to
the input of another process. You have to implement it yourself.
Implementation:
public class RedirectStreams {
public RedirectStreams(Process process1, Process process2) {
final Process tmpProcess1 = process1;
final Process tmpProcess2 = process2;
new Thread(new Runnable() {
#Override
public void run() {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(tmpProcess1.getInputStream()));
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(tmpProcess2.getOutputStream()));
String lineToPipe;
try {
while ((lineToPipe = bufferedReader.readLine()) != null){
System.out.println("Output process1 / Input process2:" + lineToPipe);
bufferedWriter.write(lineToPipe + '\n');
bufferedWriter.flush();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
}
}
This one can surely be designed nicer
and I haven't tested, if it runs's safe, but it does the job.
Usage:
RedirectStreams redirectStreams = new RedirectStreams(process1,process2);
Test:
public class ProcessPipeTest {
#Test public void testPipe(){
try {
Process process1 = new ProcessBuilder("/bin/bash").start();
Process process2 = new ProcessBuilder("/bin/bash").start();
RedirectStreams redirectStreams = new RedirectStreams(process1,process2);
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(process1.getOutputStream()));
String command = "echo echo echo";
System.out.println("Input process1: " + command);
bufferedWriter.write(command + '\n');
bufferedWriter.close();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process2.getInputStream()));
String actualOutput = bufferedReader.readLine();
System.out.println("Output process2: " + actualOutput);
assertEquals("echo",actualOutput);
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output:
Input process1: echo echo echo
Output process1 / Input process2:echo echo
Output process2: echo

As of JDK 9, you can use startPipeline like so:
ProcessBuilder.startPipeline(
Arrays.asList(
new ProcessBuilder(...),
new ProcessBuilder(...),
...
)
)

How can i execute batch file content in java on a server without window popping up

The uploaded Screenshot conatains the start_client.bat file content, viewed in notepad++ editor.
Currently am invoking start_client.bat on local machine it works fine but when the same bat file is invoked on server it pops up a window on server and it needs manual closure after execution. Any way to force bat file execution on server without window poppping up.
private void invokeSeagull(String flag) throws Exception
{
String path="";
if(flag.equals("Start"))
{
path="cmd /c start D:/Seagull/TIB/start_client.bat";
}
if(flag.equals("Stop"))
{
path="cmd /c start D:/Seagull/TIB/stop_client.bat";
}
try {
String line;
Process p = Runtime.getRuntime().exec(path);
p.waitFor();
BufferedReader bri = new BufferedReader
(new InputStreamReader(p.getInputStream()));
BufferedReader bre = new BufferedReader
(new InputStreamReader(p.getErrorStream()));
while ((line = bri.readLine()) != null) {
System.out.println(line);
}
bri.close();
while ((line = bre.readLine()) != null) {
System.out.println(line);
}
bre.close();
p.waitFor();
System.out.println("Done.");
}
catch (Exception err) {
err.printStackTrace();
}
}

This code snippet should run batch file, of course if you use Windows.
Runtime.getRuntime().exec("cmd /c start {pathToFile}");

As pointed out be ssedano the correct way to execute shell commands in Java is the Process-builder:
// Just the name of an executable is enough
final ProcessBuilder pb = new ProcessBuilder( "test.bat" );
pb.redirectError( Redirect.INHERIT );
pb.redirectOutput( Redirect.INHERIT );
System.out.println( String.format( "***** Running Process %s OUTPUT:", pb.command().toString() ) );
final Process process = pb.start();
process.getOutputStream().close();
final int returnCode = process.waitFor();
System.out.println( "***** Process Exited with Returncode: " + returnCode );
You can just redirect STDERR and STDOUT of the bat-file, so you will get all output in the Server-Output console. And you should close STDIN of the bat-file, so it will exit and not get stuck on the pause command at the end!

You could use the new in Java 7 ProcessBuilder
A simple example:
String[] command = {"CMD", "/C", "dir"};
ProcessBuilder probuilder = new ProcessBuilder(command);
// Set up your work directory
probuilder.directory(new File("c:\\stackoverflow"));
Process process = probuilder.start();
// Read output
try (InputStream is = process.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);)
{
String line;
System.out.printf("Output of running %s is:\n", Arrays.toString(command));
while ((line = br.readLine()) != null)
{
System.out.println(line);
}
// Wait to get exit value
int exitValue = process.waitFor();
}
catch (Exception e)
{
// Fail
}

This should run in the silent mode :
Runtime.getRuntime().exec(new String[] {"cmd", "/pathto/start_client.bat"});

Calling "mysqldump" with Runtime.getRuntime().exec(cmd) from Windows 7

I am trying to dump a MySQL database within my Java application the following way:
String[] command = new String[] {"cmd.exe", "/c", "C:/mysql/mysqldump.exe" --quick --lock-tables --user=\"root\" --password=\"mypwd\" mydatabase > \"C:/mydump.sql\""};
Process process = Runtime.getRuntime().exec(command);
int exitcode = process.waitFor();
The process fails with exit-code 6. I somewhere read that the operand ">" is not correctly interpreted and there was the hint to use "cmd.exe /c" as prefix. But it still doesn't work.
Any ideas?

Yes, you are right , some days ago I made class for exporting DataBase from MySQL...
You coud read output sream from console and then write to file
String[] command = new String[] {"cmd.exe", "/c", "\"C:/Program Files/MySQL/MySQL Server 5.6/bin/mysqldump.exe\" --quick --lock-tables --user=\"root\" --password=\"mypwd\" mydatabase "};
Process process = Runtime.getRuntime().exec(command);
BufferedReader input = new BufferedReader(new InputStreamReader(process.getInputStream()));
while ((line = input.readLine()) != null) {
System.out.println(line); //there you can write file
}
input.close();
Best Regards

Okay here's the final solution. You need to put the "process-reader to file-writer" code into a separate thread and finally wait for the process object to be finished:
// define backup file
File fbackup = new File("C:/backup.sql");
// execute mysqldump command
String[] command = new String[] {"cmd.exe", "/c", "C:/path/to/mysqldump.exe --quick --lock-tables --user=myuser --password=mypwd mydatabase"};
final Process process = Runtime.getRuntime().exec(command);
// write process output line by line to file
if(process!=null) {
new Thread(new Runnable() {
#Override
public void run() {
try{
try(BufferedReader reader = new BufferedReader(new InputStreamReader(new DataInputStream(process.getInputStream())));
BufferedWriter writer = new BufferedWriter(new FileWriter(fbackup))) {
String line;
while((line=reader.readLine())!=null) {
writer.write(line);
writer.newLine();
}
}
} catch(Exception ex){
// handle or log exception ...
}
}
}).start();
}
if(process!=null && process.waitFor()==0) {
// success ...
} else {
// failed
}
On Linux you can directly re-direct the output of the command to a file by using ">" as usual... (and also on Mac OS X I think). So no need for the thread. Generally, please avoid white spaces in your path to the mysqldump/mysqldump.exe file!

Running Command Line in Java [duplicate]

This question already has answers here:
Executing a Java application in a separate process
(9 answers)
Closed 7 years ago.
Is there a way to run this command line within a Java application?
java -jar map.jar time.rel test.txt debug
I can run it with command but I couldn't do it within Java.

Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("java -jar map.jar time.rel test.txt debug");
http://docs.oracle.com/javase/7/docs/api/java/lang/Runtime.html

You can also watch the output like this:
final Process p = Runtime.getRuntime().exec("java -jar map.jar time.rel test.txt debug");
new Thread(new Runnable() {
public void run() {
BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
try {
while ((line = input.readLine()) != null)
System.out.println(line);
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
p.waitFor();
And don't forget, if you are running a windows command, you need to put cmd /c in front of your command.
EDIT: And for bonus points, you can also use ProcessBuilder to pass input to a program:
String[] command = new String[] {
"choice",
"/C",
"YN",
"/M",
"\"Press Y if you're cool\""
};
String inputLine = "Y";
ProcessBuilder pb = new ProcessBuilder(command);
pb.redirectErrorStream(true);
Process p = pb.start();
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));
writer.write(inputLine);
writer.newLine();
writer.close();
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
This will run the windows command choice /C YN /M "Press Y if you're cool" and respond with a Y. So, the output will be:
Press Y if you're cool [Y,N]?Y

To avoid the called process to be blocked if it outputs a lot of data on the standard output and/or error, you have to use the solution provided by Craigo. Note also that ProcessBuilder is better than Runtime.getRuntime().exec(). This is for a couple of reasons: it tokenizes better the arguments, and it also takes care of the error standard output (check also here).
ProcessBuilder builder = new ProcessBuilder("cmd", "arg1", ...);
builder.redirectErrorStream(true);
final Process process = builder.start();
// Watch the process
watch(process);
I use a new function "watch" to gather this data in a new thread. This thread will finish in the calling process when the called process ends.
private static void watch(final Process process) {
new Thread() {
public void run() {
BufferedReader input = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line = null;
try {
while ((line = input.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}.start();
}

Runtime.getRuntime().exec("java -jar map.jar time.rel test.txt debug");

import java.io.*;
Process p = Runtime.getRuntime().exec("java -jar map.jar time.rel test.txt debug");
Consider the following if you run into any further problems, but I'm guessing that the above will work for you:
Problems with Runtime.exec()

what about
public class CmdExec {
public static Scanner s = null;
public static void main(String[] args) throws InterruptedException, IOException {
s = new Scanner(System.in);
System.out.print("$ ");
String cmd = s.nextLine();
final Process p = Runtime.getRuntime().exec(cmd);
new Thread(new Runnable() {
public void run() {
BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
try {
while ((line = input.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
p.waitFor();
}
}

Have you tried the exec command within the Runtime class?
Runtime.getRuntime().exec("java -jar map.jar time.rel test.txt debug")
Runtime - Java Documentation

Process p = Runtime.getRuntime().exec("java -jar map.jar time.rel test.txt debug");

Java Process IO

Im using java to start a GNOME terminal process in linux and redirecting its input and output to my code. Below is a code.
public static void main(String[] args) throws InterruptedException
{
// TODO Auto-generated method stub /usr/bin/telnet
try
{
String line, commandInput;
Scanner scan = new Scanner(new File("/home/Ashutosh/Documents/testfile"));
ProcessBuilder telnetProcessBuilder = new ProcessBuilder("/bin/bash");///home/Ashutosh/Documents/tempScript");
telnetProcessBuilder.redirectErrorStream(true);
Process telnetProcess = telnetProcessBuilder.start();
//Process telnetProcess = Runtime.getRuntime().exec("xterm");///home/Ashutosh/Documents/tempScript");
BufferedReader input = new BufferedReader(new InputStreamReader(telnetProcess.getInputStream()));
BufferedWriter output = new BufferedWriter(new OutputStreamWriter(telnetProcess.getOutputStream()));
while(scan.hasNext())
{
commandInput = scan.nextLine();
output.write(commandInput);
/* if(commandInput.trim().equals("exit"))
{
output.write("exit\r");
}
else
{
output.write("((" + commandInput + ") && echo --EOF--) || echo --EOF--\r");
}
*/ output.flush();
line = input.readLine();
while(line != null && !line.trim().equals("--EOF--"))
{
System.out.println(line);
line = input.readLine();
}
if(line == null)
break;
}
/* Thread.sleep(500);
output.write("/home/Ashutosh/Documents/testfile\r");
Thread.sleep(500);
output.flush();
while((line = input.readLine())!= null)
System.out.println(line);
telnetProcess.destroy();
*/ //String s = input.readLine();
//System.out.print(s + "\r\n");
//s = input.readLine();
//System.out.print(s + "\r\n");
}
the contents of testfile which is bash script is
#!/bin/bash
ls -l
pwd
date
exit
and i also tried the following interactive script which takes input from user which i want to redirect from java code is given
#! /bin/bash
echo "Input any number form 0-3:"
read num
case $num in
0) echo "You are useless";;
1) echo "You are number 1";;
2) echo "Too suspecious";;
3) echo "Thats all man, got to go...!";;
*) echo "Cant't u read english, this is wrong choice";;
esac
read
exit
my code stops at input.readLine(); im not sure but i think i am not able to redirect the output stream
output.write(commandInput);
command is executing well but did not write i intended to on the process redirected input, that is why it hangs at readLine();.
If somebody have already solved please let me know the solution.
From following link i tried to solve the issue but still no luck:
Java Process with Input/Output Stream
Thanks
Ashutosh

readLine() read the contents of a line, without the newline at the end.
write() writes just the text, it doesn't add a new line.
Perhaps you want to add write("\n"); or use PrintStream or PrintWriter.
I imagine, your script is being sent as
#!/bin/bashls -lpwddateexit
which is a comment without a newline.

EDIT: Huge error, not adding the command to the ProcessBuilder!!
Why are you not just running your script as a Linux script? That is,
ProcessBuilder builder = new ProcessBuilder();
LinkedList<String> command = new LinkedList<String>();
command.add("/bin/bash");
command.add("/home/Ashutosh/Documents/testfile");
builder.command(command);
Process myProc = builder.start();
Also, I notice the variable is named 'telnetProcess' yet there is no invocation of telnet anywhere that I can see. Perhaps this is the problem?
EDIT: Added my suggestion below for the interactive script.
ProcessBuilder builder = new ProcessBuilder();
LinkedList<String> command = new LinkedList<String>();
command.add("/bin/bash");
command.add("/path/to/interactiveScript");
builder.command(command);
final Process myProc = builder.start();
// Java input goes to process input.
Thread inputParser = new Thread() {
public void run() {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(myProc.getOutputStream()));
String line = "";
while(line != null) {
line = br.readLine();
bw.write(line);
bw.newLine();
}
}
}.start();
// Process output must go to Java output so user can see it!
Thread outputParser = new Thread() {
public void run() {
BufferedReader br = new BufferedReader(new InputStreamReader(myProc.getInputStream()));
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
String line = "";
while(line != null) {
line = br.readLine();
bw.write(line);
bw.newLine();
}
}
}.start();

hi guys sorry for late response, after some trials i got it working. I am simply letting the process completing its process and exit normally rather than forcefully and then the BufferedReader and BufferedWriter keeps the string buffers in RAM which i can read now after process exit with code 0.
public static void main(String[] args) throws InterruptedException
{
// TODO Auto-generated method stub
try
{
String line, commandInput;
ProcessBuilder telnetProcessBuilder = new ProcessBuilder("/bin/bash");
telnetProcessBuilder.redirectErrorStream(true);
Process telnetProcess = telnetProcessBuilder.start();
BufferedReader input = new BufferedReader(new InputStreamReader(telnetProcess.getInputStream()));
BufferedWriter output = new BufferedWriter(new OutputStreamWriter(telnetProcess.getOutputStream()));
commandInput = "ls -l\n";
output.write(commandInput);
output.flush();
commandInput = "pwd\n";
output.write(commandInput);
output.flush();
commandInput = "whoami\n";
output.write(commandInput);
output.flush();
commandInput = "exit\n";
output.write(commandInput);
output.flush();
while((line = input.readLine())!= null)
System.out.println(line);
}
}