This question already has answers here:
Execute external program through terminal in Java
(4 answers)
Executing another java program from our java program [duplicate]
(3 answers)
Closed 4 years ago.
Using
String cmdString = "cmd.exe /c start python ";
Process p = Runtime.getRuntime().exec(cmdString);
I can open the command prompt and run python. I now want to interact with the command prompt. I have read that using
public static void main(String[] args)
{
BufferedWriter writerToProc;
String scriptPath = "C:\\Users\\MichaelMi\\Documents\\SourceTree\\NODE-Sensor-Configurator\\src\\application\\resources\\BACnet-CMD-Line-Upgrader\\UpgradeApplication.py";
String iniPath = "C:\\Users\\MichaelMi\\Documents\\SourceTree\\NODE-Sensor-Configurator\\src\\application\\resources\\BACnet-CMD-Line-Upgrader\\BACpypes.ini";
String execString = "python " + scriptPath + " --ini " + iniPath;
String cmdString = "cmd.exe /c start " + execString ;
try {
Process p = Runtime.getRuntime().exec(cmdString);
writerToProc = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));
writerToProc.write(cmdString);
writerToProc.flush();
writerToProc.write("whois\n");
writerToProc.flush();
readErrors(p);
readOutput(p);
} catch (IOException e) {
e.printStackTrace();
}
}
public static void readOutput(Process p)
{
BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
Runnable task = new Runnable() {
#Override
public void run() {
try {
if(stdInput.ready())
{
stdInput.lines().forEach((l) -> System.out.println(l));
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
Thread backgroundThread = new Thread(task);
backgroundThread.setDaemon(true);
backgroundThread.start();
}
public static void readErrors(Process p)
{
BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));
Runnable task = new Runnable() {
#Override
public void run() {
try {
if(stdError.ready())
{
stdError.lines().forEach((l) -> System.out.println(l));
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
Thread backgroundThread = new Thread(task);
backgroundThread.setDaemon(true);
backgroundThread.start();
}
Is supposed to allow me to write to the open command prompt. However this is not working for me. I am getting no exceptions thrown or status errors. I simply do not know how to write to an open command prompt.
I see two problems in your code:
One problem is the used command-line:
cmd.exe /c start python This starts a new cmd.exe instance which itself the uses start to start a detached python process. The detached process is therefore not connected to your BufferedReader/BufferedWriter.
Your second problem is that python does not execute your "1+1" via stdin.
You can simply verify that by creating a file test with the context 1+1\n and execute it on the console: python < test. You will see no output.
See also piping from stdin to a python code in a bash script.
In this case you need to close the input stream before you can read the output streams of the python process. If anyone knows a better way please let us know.
public static void main(String[] args) {
String cmdString = "python";
try {
ProcessBuilder pb = new ProcessBuilder(cmdString);
Process pr = pb.start();
try (BufferedReader readerOfProc = new BufferedReader(
new InputStreamReader(pr.getInputStream()));
BufferedReader errorsOfProc = new BufferedReader(
new InputStreamReader(pr.getErrorStream()))) {
try (BufferedWriter writerToProc = new BufferedWriter(
new OutputStreamWriter(pr.getOutputStream()));) {
writerToProc.write("myVar=1+1\r\n");
writerToProc.write("print(myVar)\r\n");
writerToProc.flush();
} catch (Exception e) {
e.printStackTrace();
}
String s;
while ((s = readerOfProc.readLine()) != null) {
System.out.println("stdout: " + s);
}
while ((s = errorsOfProc.readLine()) != null) {
System.out.println("stdout: " + s);
}
System.out.println("exit code: " + pr.waitFor());
}
} catch (Exception e) {
e.printStackTrace();
}
}
Hope this helps!
I have a Java Swing class from which I want my Java application to run a local python program after clicking a button. The following code does not run the executable python I have created.
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
try {
// TODO add your handling code here:
Process process =
Runtime.getRuntime().exec("C:\\Users\\User\\Desktop\\hello.exe");
} catch (IOException ex) {
Logger.getLogger(NewJFrame.class.getName()).log(Level.SEVERE, null, ex);
}
}
I have even tried running the python script file using:
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
try {
Process p= Runtime.getRuntime().exec("C:\\Python27\\python.exe \"C:\\Users\\User\\Desktop\\hello.py\"");
} catch (IOException ex) {
Logger.getLogger(NewJFrame.class.getName()).log(Level.SEVERE, null, ex);
}
}
I have no errors yet neither does the job. I can run applications like notepad etc using the same syntax, however I cant with python and I'm unsure how to resolve this.
P.s. I do have Python 2.7 PATH in my environment variable. Also, the above are just the methods for the action performed by the buttons. I have all the other methods and main class in my full program.
Process p= Runtime.getRuntime().exec("cmd /c /K \"C:\\Python27\\python.exe C:\\Users\\User\\Desktop\\hello.py\"");
do this way.. call the Python from cmd
I tried this simple example & it worked for me...
Files : CallPython.java & hello.py
CallPython.java
import java.util.*;
import java.io.*;
class CallPython{
public static void main(String args[]){
try{
Process proc= Runtime.getRuntime().exec("python hello.py");
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);
}
*/
stdInput.lines().forEach(System.out::println);
}
catch(IOException e){
System.err.println("Error occured while executing an external process...");
}
}
}
hello.py
print('Hello...from python script');
Output:
Hello...from python script
Java is new to me.
I am executing a batch file using Runtime.getRuntime.exec(filename.bat) and this batch file executes a commandant encrypt.password -Dvalue=somevalue>log.txt and redirects its output to a log.txt file.
Problem that I am facing is batch file is working fine if I run it manually however when program executes it ,it just creates blank 'log.txt'
Content of mybat.bat batch file is as below:
cd/
c:
cd c:/ant_builds/thinclient
ant encrypt.password -Dvalue=someValue >C:/log.txt
Java code is as below:
Process p=Runtime.getRuntime.exec("C:\mybat.bat");
p.waitFor();
It seems that after creating the log file,meantime command is executing control comes out from process.
I have read almost 50 threads here however did not get the solution. Please help me out.
Use ProcessBuilder to create your process and call redirectOutput(File) to redirect and append output to a file.
Try this code:
public class Test {
ProcessBuilder builder;
Path log;
public Test() {
try
{
log = Paths.get("C:\\log.txt");
if (!Files.exists(log))
{
Files.createFile(log);
}
builder = new ProcessBuilder("ant", "encrypt.password", "-Dvalue=someValue");
builder.directory(Paths.get("C:\\ant_builds\\thinclient").toFile());
builder.redirectOutput(ProcessBuilder.Redirect.appendTo(log.toFile()));
builder.start();
}
catch (IOException e)
{
e.printStackTrace();
}
}
public static void main(String[] args) {
new Test();
}
}
For jdk 1.6 or less, use the following code:
public class Test {
ProcessBuilder builder;
Path log;
Process process;
BufferedReader br;
PrintWriter pw;
Charset charset = Charset.forName("UTF-8");
public Test() {
try {
log = new File("C:\\log.txt");
if (!log.exists()) {
log.createNewFile();
}
builder = new ProcessBuilder("ant", "encrypt.password","-Dvalue=someValue");
builder.directory(new File("C:\\ant_builds\\thinclient"));
builder.redirectErrorStream(true);
process = builder.start();
br = new BufferedReader(new InputStreamReader(process.getInputStream(),charset));
pw = new PrintWriter(new OutputStreamWriter(new FileOutputStream(log, true), charset));
(new Thread() {
public void run() {
try {
while (process.isAlive()) {
String s = null;
while ((s = br.readLine()) != null) {
pw.print(s);
pw.flush();
}
}
br.close();
pw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
new Test();
}
}
I'm not sure about the order and list of ProcessBuilder arguments so try to play with them to get your code working.
You can also read commands from a common file and redirect output and erros to a sepearate files. Redirect.appendTo is to avoid the process from overiting the existing logs.
Try this code:
try {
File commands = new File("D:/Sample/Commands.txt");
File output = new File("D:/Sample/Output.txt");
File errors = new File("D:/Sample/ErrorsLog.txt");
ProcessBuilder pb = new ProcessBuilder("cmd");
System.out.println(pb.redirectInput());
System.out.println(pb.redirectOutput());
System.out.println(pb.redirectError());
pb.redirectInput(commands);
pb.redirectError(Redirect.appendTo(errors));
pb.redirectOutput(Redirect.appendTo(output));
pb.redirectInput();
pb.redirectOutput();
pb.redirectError();
pb.start();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I made this code to move a folder then hardlink it to it's original destination. The problem it works fully when I'm just trying it from eclipse but when I make it into it's own self executing jar it wont create the hardlink but it will move the folder. The code runs a command line and then enters the commands. I dont know ehy the move command works and not the other one. Please help.
(Mklink command)
import java.io.*;
import javax.swing.JOptionPane;
public class The_Cloud_Setup {
public static void main(String[] args) throws IOException
{
try {
String command = "c:\\cmd.exe";
Runtime.getRuntime().exec(command);
}
catch (IOException e){
JOptionPane.showMessageDialog(null , e.getMessage(), "End Result", 2);
System.err.println(e.getMessage());
}
String[] StringMove = { "cmd.exe", "/c", "move"+" "+"\"C:/Users/%username%/Documents/My Games/Terraria/Players\""+" "+"\"C:/Users/%username%/Google Drive/Players\""};
String[] StringMklink = {"cmd.exe", "/c", "mklink"+" "+"/d"+" "+"\"C:/Users/%username%/Documents/My Games/Terraria/Players\""+" "+"\"C:/Users/%username%/Google Drive/Players\""};
Process ProcessMove = Runtime.getRuntime().exec(StringMove);
Process ProcessMklink = Runtime.getRuntime().exec(StringMklink);
BufferedReader VarMove = new BufferedReader(new InputStreamReader(ProcessMove.getInputStream()));
BufferedReader VarMklink = new BufferedReader(new InputStreamReader(ProcessMklink.getInputStream()));
String temp = "";
while ((temp = VarMove.readLine()) != null) {
System.out.println(temp);
}
VarMove.close();
VarMklink.close();
}
}
Most likely, when you are running natively, the move command has not completed before your program attempts to execute the mklink command. You can't make a link where there is an existing folder.
I want to create diff of two files. I tried searching for code in Java that does it, but didnt find any simple code/ utility code for this. Hence, I thought if I can somehow run linux diff/sdiff command from my java code and make it return a file that stores the diff then it would be great.
Suppose there are two files fileA and fileB. I should be able to store their diff in a file called fileDiff through my java code. Then fetching data from fileDiff would be no big deal.
You can use java.lang.Runtime.exec to run simple code. This gives you back a Process and you can read its standard output directly without having to temporarily store the output on disk.
For example, here's a complete program that will showcase how to do it:
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class testprog {
public static void main(String args[]) {
String s;
Process p;
try {
p = Runtime.getRuntime().exec("ls -aF");
BufferedReader br = new BufferedReader(
new InputStreamReader(p.getInputStream()));
while ((s = br.readLine()) != null)
System.out.println("line: " + s);
p.waitFor();
System.out.println ("exit: " + p.exitValue());
p.destroy();
} catch (Exception e) {}
}
}
When compiled and run, it outputs:
line: ./
line: ../
line: .classpath*
line: .project*
line: bin/
line: src/
exit: 0
as expected.
You can also get the error stream for the process standard error, and output stream for the process standard input, confusingly enough. In this context, the input and output are reversed since it's input from the process to this one (i.e., the standard output of the process).
If you want to merge the process standard output and error from Java (as opposed to using 2>&1 in the actual command), you should look into ProcessBuilder.
You can also write a shell script file and invoke that file from the java code. as shown below
{
Process proc = Runtime.getRuntime().exec("./your_script.sh");
proc.waitFor();
}
Write the linux commands in the script file, once the execution is over you can read the diff file in Java.
The advantage with this approach is you can change the commands with out changing java code.
You need not store the diff in a 3rd file and then read from in. Instead you make use of the Runtime.exec
Process p = Runtime.getRuntime().exec("diff fileA fileB");
BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
}
try to use unix4j. it s about a library in java to run linux command. for instance if you got a command like:
cat test.txt | grep "Tuesday" | sed "s/kilogram/kg/g" | sort
in this program will become:
Unix4j.cat("test.txt").grep("Tuesday").sed("s/kilogram/kg/g").sort();
You can call run-time commands from java for both Windows and Linux.
import java.io.*;
public class Test{
public static void main(String[] args)
{
try
{
Process process = Runtime.getRuntime().exec("pwd"); // for Linux
//Process process = Runtime.getRuntime().exec("cmd /c dir"); //for Windows
process.waitFor();
BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line;
while ((line=reader.readLine())!=null)
{
System.out.println(line);
}
}
catch(Exception e)
{
System.out.println(e);
}
finally
{
process.destroy();
}
}
}
Hope it Helps.. :)
Runtime run = Runtime.getRuntime();
//The best possible I found is to construct a command which you want to execute
//as a string and use that in exec. If the batch file takes command line arguments
//the command can be constructed a array of strings and pass the array as input to
//the exec method. The command can also be passed externally as input to the method.
Process p = null;
String cmd = "ls";
try {
p = run.exec(cmd);
p.getErrorStream();
p.waitFor();
}
catch (IOException e) {
e.printStackTrace();
System.out.println("ERROR.RUNNING.CMD");
}finally{
p.destroy();
}
The suggested solutions could be optimized using commons.io, handling the error stream, and using Exceptions. I would suggest to wrap like this for use in Java 8 or later:
public static List<String> execute(final String command) throws ExecutionFailedException, InterruptedException, IOException {
try {
return execute(command, 0, null, false);
} catch (ExecutionTimeoutException e) { return null; } /* Impossible case! */
}
public static List<String> execute(final String command, final long timeout, final TimeUnit timeUnit) throws ExecutionFailedException, ExecutionTimeoutException, InterruptedException, IOException {
return execute(command, 0, null, true);
}
public static List<String> execute(final String command, final long timeout, final TimeUnit timeUnit, boolean destroyOnTimeout) throws ExecutionFailedException, ExecutionTimeoutException, InterruptedException, IOException {
Process process = new ProcessBuilder().command("bash", "-c", command).start();
if(timeUnit != null) {
if(process.waitFor(timeout, timeUnit)) {
if(process.exitValue() == 0) {
return IOUtils.readLines(process.getInputStream(), StandardCharsets.UTF_8);
} else {
throw new ExecutionFailedException("Execution failed: " + command, process.exitValue(), IOUtils.readLines(process.getInputStream(), StandardCharsets.UTF_8));
}
} else {
if(destroyOnTimeout) process.destroy();
throw new ExecutionTimeoutException("Execution timed out: " + command);
}
} else {
if(process.waitFor() == 0) {
return IOUtils.readLines(process.getInputStream(), StandardCharsets.UTF_8);
} else {
throw new ExecutionFailedException("Execution failed: " + command, process.exitValue(), IOUtils.readLines(process.getInputStream(), StandardCharsets.UTF_8));
}
}
}
public static class ExecutionFailedException extends Exception {
private static final long serialVersionUID = 1951044996696304510L;
private final int exitCode;
private final List<String> errorOutput;
public ExecutionFailedException(final String message, final int exitCode, final List<String> errorOutput) {
super(message);
this.exitCode = exitCode;
this.errorOutput = errorOutput;
}
public int getExitCode() {
return this.exitCode;
}
public List<String> getErrorOutput() {
return this.errorOutput;
}
}
public static class ExecutionTimeoutException extends Exception {
private static final long serialVersionUID = 4428595769718054862L;
public ExecutionTimeoutException(final String message) {
super(message);
}
}
if the opening in windows
try {
//chm file address
String chmFile = System.getProperty("user.dir") + "/chm/sample.chm";
Desktop.getDesktop().open(new File(chmFile));
} catch (IOException ex) {
Logger.getLogger(Frame.class.getName()).log(Level.SEVERE, null, ex);
{
JOptionPane.showMessageDialog(null, "Terjadi Kesalahan", "Error", JOptionPane.WARNING_MESSAGE);
}
}
ProcessBuilder processBuilder = new ProcessBuilder();
// -- Linux --
// Run a shell command
processBuilder.command("bash", "-c", "ls /home/kk/");
// Run a shell script
//processBuilder.command("path/to/hello.sh");
// -- Windows --
// Run a command
//processBuilder.command("cmd.exe", "/c", "dir C:\\Users\\kk");
// Run a bat file
//processBuilder.command("C:\\Users\\kk\\hello.bat");
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) {
System.out.println("Success!");
System.out.println(output);
System.exit(0);
} else {
//abnormal...
}
} catch (IOException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}