I was able to capture the logcat output using below java code in android.
public void WriteLogCatOutput() {
StringBuilder log;
log=new StringBuilder();
try {
Process process = Runtime.getRuntime().exec("logcat -d");
BufferedReader bufferedReader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
String line;
while ((line = bufferedReader.readLine()) != null) {
log.append(line);
}
} catch (IOException e) {
}
I can keep reading the logs, just by removing the "-d" flag in code above and placing it in a thread.
But is that possible to read the logcat outputs just with TWO calls/one call to the above method, so that we can capture the logcat output from the start of my JUnitTest and towards the end of JUnit Test and get only the logcat output in between?
Related
I have to execute a command from Java program on Unix platform.
I am using Runtime.getRuntime() for it.
However, the problem is that my command is interactive and asks for certain parameters at runtime. For e.g., the command is createUser. It asks for userName as the runtime.
bash-4.1$ createUser
Enter the UserName:
How can I handle such scenario so that the user name is entered at runtime from Java program?
try {
Process proc;
proc = Runtime.getRuntime().exec(cmd, envp);
BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream()));
BufferedReader stdError = new BufferedReader(new InputStreamReader(proc.getErrorStream()));
// read the output from the command
String s = null;
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
sb.append(s);
}
// read any errors from the attempted command
while ((s = stdError.readLine()) != null) {
System.out.println(s);
sb.append(s);
}
} catch (Exception e) {
e.printStackTrace();
sb = null;
}
I heard that it can be done through expect. But How can I do it in Java?
Get also the standardOutput from proc. All you write in that standardOutput goes to the command
Send the username to standardOutput and don't forget to send the \n too.
You can check what was the last line of input steam and when you detect the prompt for user input input write to the output steam your value.
try {
Process proc;
proc = Runtime.getRuntime().exec(cmd, envp);
final BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream()));
final PrintWriter stdOutput = new PrintWriter(proc.getOutputStream());
// read the output from the command
String s = null;
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
if (s.equals("Enter your username")) {
stdOutput.println("MyUsername");
stdOutput.flush();
}
sb.append(s);
}
} catch (final Exception e) {
e.printStackTrace();
sb = null;
}
(removed the error stream for simplicity)
Note that this works only if the prompt ends with a new line.
If the prompt has no new line (eg. Username: <cursor here>) you can try just writing the value at the start:
...
final PrintWriter stdOutput = new PrintWriter(proc.getOutputStream());
stdOutput.println("MyUsername");
stdOutput.flush();
...
But if the the command clears the buffer this will no work, in that case (rare case) you have to change the way you read from the stream (eg. instead of lines, read bytes)
I am writing a Java application in IntelliJ IDE. The application used Rserve package to connect to R and perform some functions. When I want to run my code for the first time, I have to launch R in the command line and start the Rserve as a daemon, which looks something like this:
R
library(Rserve)
Rserve()
After doing this, I can easily access all the function in R without any errors. However, since this Java code would be bundled as an executable file, so is there a way that Rserve() is invoked automatically as soon as the code is run so that I have to skip this manual step of starting Rserve using the command line?
Here is the code for the Class I wrote to get Rserve working from Java
public class InvokeRserve {
public static void invoke() {
String s;
try {
// run the Unix ""R CMD RServe --vanilla"" command
// using the Runtime exec method:
Process p = Runtime.getRuntime().exec("R CMD RServe --vanilla");
BufferedReader stdInput = new BufferedReader(new
InputStreamReader(p.getInputStream()));
BufferedReader stdError = new BufferedReader(new
InputStreamReader(p.getErrorStream()));
// read the output from the command
System.out.println("Here is the standard output of the command:\n");
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);
}
// System.exit(0);
}
catch (IOException e) {
System.out.println("exception happened - here's what I know: ");
e.printStackTrace();
System.exit(-1);
}
}
}
I know this question has been asked a long back . I think You have the answer. But the below answer may help others. That's why I am posting my answer.
answer:- Instead of going again and again to the R console to start Rserve. One thing you can do is you can write a java program to start Rserve.
Below code you can use in a java program to start Rserve.
https://www.sitepoint.com/community/t/call-linux-command-from-java-application/3751. This is the link where you will get the code to run a linux command from java.I have changed the command only and posting below.
package javaapplication13;
import java.io.*;
public class linux_java {
public static void main(String[] args) {
try {
String command ="R CMD Rserve";
BufferedWriter out = new BufferedWriter(new FileWriter(
new File(
"/home/jayshree/Desktop/testqavhourly.tab"), true));
final Process process = Runtime.getRuntime().exec(command);
BufferedReader buf = new BufferedReader(new InputStreamReader(
process.getInputStream()));
String line;
while ((line = buf.readLine()) != null) {
out.write(line);
out.newLine();
}
buf.close();
out.close();
int returnCode = process.waitFor();
System.out.println("Return code = " + returnCode);
} catch (Exception e) {
e.printStackTrace();
}
}
}
I'm currently making firefox addon development GUI tool using Java. However I am stuck when trying to get output of a .bat file.
When I run .bat file using java I can see the output, but there are 3 commands written in the bat file. When first command executes I can get the output simultaneously. But when it execute second command output not coming. And when .bat file exist I get all the output which didn't come simultaneously.
I'm getting output immediately when it execute:
call "C:\mozilla-build\addon-sdk-1.16\bin\activate.bat
But I'm not getting output simultaneously for following command:
call cfx run
But I know it's executing because firefox window pops up. I get all the output suddenly when I execute proc.destroy();
This is my bat file:
#echo off
call %1
cd C:\Users\Madhawa.se\Desktop\workingfox\beauty
call cfx run
pause
This is my Java code:
Thread t = new Thread(new Runnable() {
#Override
public void run() {
try {
Runtime rt = Runtime.getRuntime();
String[] commands = {"C:\\Users\\Madhawa.se\\Desktop\\workingfox\\runner\\foxrun.bat", "C:\\mozilla-build\\addon-sdk-1.16\\bin\\activate.bat"};
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
String s = null;
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
}
// read any errors from the attempted command
while ((s = stdError.readLine()) != null) {
System.out.println(s);
}
proc.waitFor();
System.out.println("success");
} catch (Exception ex) {
ex.printStackTrace();
}
}
});
t.start();
How to get output immediately and why it acts differently for this command?
i was able to fix it using process builder instead of runtime.exec .and inheriteIo doesn't work .it blocks the realtime output
Thread t = new Thread(new Runnable() {
private String s;
#Override
public void run() {
try {
Component selectedComponent = jTabbedPane2.getSelectedComponent();
if (selectedComponent instanceof MyTextArea) {
String response = "";
System.out.println("yes");
MyTextArea temptextarea = (MyTextArea) selectedComponent;
String xpiPath = new File(temptextarea.getNameX()).getParentFile().getPath();
String[] commands = {"C:\\Users\\Madhawa.se\\Desktop\\workingfox\\runner\\foxrun.bat", "C:\\mozilla-build\\addon-sdk-1.16\\bin\\activate.bat
ProcessBuilder process = new ProcessBuilder(commands);
process.redirectErrorStream(true);
Process shell = process.start();
//shell.waitFor();
BufferedReader stdInput = new BufferedReader(new InputStreamReader(shell.getInputStream()));
BufferedReader stdError = new BufferedReader(new InputStreamReader(shell.getErrorStream()));
// read the output from the command
System.out.println("Here is the standard output of the command:\n");
while ((s = stdInput.readLine()) != null) {
System.out.println("s:" + 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("w:" + s);
}
}
} catch (Exception ex) {
ex.printStackTrace();
}
I have a weird problem when trying to execute a shell command from within a java program. Since there exist thousands of websites that explain how to do it I used the following recommended code:
public String executeShellCommand (String command)
{
try
{
StringBuffer sb = new StringBuffer();
String line = "";
Process p = Runtime.getRuntime().exec(command);
BufferedReader reader = new BufferedReader(new InputStreamReader(
p.getInputStream()));
while ((line = reader.readLine()) != null)
sb.append(line + "\n");
p.waitFor();
return sb.toString();
}
catch (Exception e)
{
e.printStackTrace();
}
return null;
}
Acutally, when I try to execute for instance ls -aF is works fine and I get some output as a result. Therefore I'm pretty sure that the above code is, in principal, correct. However, I got another program I'd like to run and that produces a file as an output. I would like to execute it the above way but it never is executed and no output file is generated. Also I do not get any error, warnings or whatsoever in java. When copy and pasting the actual command argument string into the console the execution of the programm/command directly in the shell works fine and the output file is generated. So the command I pass to the method is also correct.
Are there additional things I need to pay attention to when trying to execute a shell command from within java?
UPDATE: I modified my code according to the suggestions. However, it is still hanging:
public String executeShellCommand(List<String> command, String logfile, boolean waitForProcess) { try {
ProcessBuilder pb = new ProcessBuilder(command);
System.out.println("pb.toString() = " + pb.toString());
Process p = pb.start();
System.out.println("2");
BufferedReader err = new BufferedReader(new InputStreamReader(p.getErrorStream()));
BufferedReader out = new BufferedReader(new InputStreamReader(p.getInputStream()));
System.out.println("3");
StringBuilder errSb = new StringBuilder();
StringBuilder outSb = new StringBuilder();
String line;
System.out.println("4");
while ((line = err.readLine()) != null) { // <--- code hangs here
errSb.append(line + "\n");
System.out.println("errSb = " + errSb.toString());
}
System.out.println("4a");
while ((line = out.readLine()) != null) {
outSb.append(line + "\n");
System.out.println("outSb = " + outSb.toString());
}
System.out.println("5");
if(waitForProcess) {
System.out.println("Wait for process");
p.waitFor();
} else {
System.out.println("Sleep 5000");
Thread.sleep(5000);
}
System.out.println("6");
//Log result to file
if(logfile != null) {
OutputStreamWriter outWriter = new OutputStreamWriter(new FileOutputStream(logfile));
outWriter.write(errSb.toString());
outWriter.close();
}
return errSb.toString();
} catch(Exception e) { e.printStackTrace(); } return null; }
This will block if your command writes too many characters to stderr. Like for sdtout, Java redirect stderr through a pipe, and if you do not read the pipe, it can fill up and block (size of the pipe is probably less than 256 bytes). To avoid that, you need to read from the Process.getErrorStream(), preferable from another thread as the main thread is busy reading from the Process.getInputStream().
A simpler way to avoid that is to use the ProcessBuilder class instead of Runtime.exec() and ProcessBuilder.redirectErrorStream(true) so that both stdout and stderr are merged into the Process.getInputStream()
As per Process javadoc :
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.
You are calling p.waitFor(). If we carefully read the waitFor() documentation:
Causes the current thread to wait, if necessary, until the process represented by this Process object has terminated.
You are waiting for a process which hangs, because its error stream and output stream are never read.
What you should do, is to read these streams:
p.start();
BufferedReader err= new BufferedReader(new InputStreamReader(p.getErrorStream()));
BufferedReader out = new BufferedReader(new InputStreamReader(p.getOutputStream()));
StringBuilder errSb = new StringBuilder();
StringBuilder outSb = new Stringbuilder();
String line;
while ((line = err.readLine()) != null) {
errSb.append(line);
}
while ((line = out.readLine()) != null) {
outSB.append(line);
}
int retCode = p.waitFor(); //0 for success
System.out.println(retCode);
System.err.println(errSB.toString());
You should always read the error stream when calling external programs via the Process class, else you may find yourself in this odd situation where a process hangs forever. (well until someone else -the operating system, another application, etc- kills it, more exactly).
I've also noticed that you use the Runtime.getRuntime() which is not the recommended way to run external programs, starting with java 1.5, as per javadoc:
As of 1.5, ProcessBuilder.start() is the preferred way to create a Process.
ProcessBuilder pb = new ProcessBuilder("ls" , "-aF");
Process p = pb.start();
I'm looking for a solution to print the output and error streams on the windows console.
A java program starts a rcp application (.exe) thanks to a command line :
Runtime.getRuntime.exec("example.exe");
Example.exe writes something after being started...
Then I want the java program to get the output stream of example.exe.
My problem is that it doesn't work and if I put the 2 eclipse runtime options: -console and -consoleLog, the output stream is printed in another console so I can't get back the stream...
Any ideas?
Edit: Here is my code to get the outputStream and errorStream (it works for a simple java program but not for a rcp application)
final Process process = Runtime.getRuntime().exec("toto.exe");
new Thread() {
public void run() {
try {
BufferedReader inputReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
BufferedReader errorReader = new BufferedReader(new InputStreamReader(process.getErrorStream()));
String line = "";
try {
while((line = inputReader.readLine()) != null) {
inputText = inputText + line;
}
System.out.println(inputText);
while((line = errorReader.readLine()) != null) {
errorText = errorText + line;
}
System.out.println(errorText);
} finally {
errorReader.close();
inputReader.close();
}
} catch(IOException ioe) {
ioe.printStackTrace();
}
}
}.start();