I'm trying to give to my app self update ability.
It download an JAR from my website and save it as myapp.jar.new.
After that, I want to launch a command to delete the current version and rename the new one.
This is my code (see the notes):
public void applyUpdateAndRestart() {
Runtime rt = Runtime.getRuntime();
rt.addShutdownHook(new Thread(() -> {
try {
String updateCmd = "restart.cmd";
try (PrintStream ps = new PrintStream(new FileOutputStream(updateCmd))) {
ps.println("#echo off");
// wait for a while to the main process closes and the "myapp.jar" to be writable
ps.println("ping 127.0.0.1 -n 2 > nul");
ps.println("del /q myapp.jar.old");
ps.println("move myapp.jar myapp.jar.old");
ps.println("move myapp.jar.new myapp.jar");
ps.println("java -jar myapp.jar");
}
ProcessBuilder p = new ProcessBuilder();
p.command("cmd", "/c", updateCmd);
System.out.println("Before apply update");
p.start(); // this does not launch
System.out.println("After apply update"); // this prints!
} catch (Throwable e) {
e.printStackTrace(); // this does not occurs!
}
}));
System.exit(0);
}
Why my update.cmd does not start?
Solved with this approach:
After download my jar to new-myapp.jar, I launch it with an special argument like this: java -jar new-myapp.jar --do-update (running the new jar will unlock the current to be overwritten)
My main mehtod intercept the argument --do-update who applies the new jar to current (copy new-myapp.jar myapp.jar).
After the new jar was copied, It launches itself again using the overwritten jar (java -jar myapp.jar)
I think that Klitos comment can solve my problem too, but I solved implementing my previous approach.
On the approach of the question the problem was that the cmd /c haven't a console window allocated. Changing the command to cmd /c start solve the problem too because the start command allocate a new console window.
My idea - since you just call start() for process and finish the shutdown hook - the process dies with your main java process. Try to call Process.waitFor() to have you shutdown hook thread waiting until external process finished.
I think that you can't do it like you want. You want to remove the jar of the application but the app is running and therefore could not be removed.
My suggestion is use a launcher.cmd that look for a new.jar if it finds it remove old.jar and rename new.jar and THEN launch java -jar old.jar.
Related
I use terminal command "java -jar secondApp.jar" inside my java file to start a secondApp.jar.
I need secondApp.jar to run even if first app is killed.
This scenario works perfectly in windows environment. But when I test this in linux environment(Ubuntu 16.04) it seems that killing the first process kills the both processes.
This is the code I use to start the second app.
String command = "java -jar secondApp.jar"
Process process = Runtime.getRuntime().exec(command);
What am I doing wrong?
Prepare a batch file and a linux script file with the desired java command, then try this:
if (SystemUtils.IS_OS_WINDOWS) {
// run batch file
String batchFullPath = new File("C:\\myBatchFile.bat").getAbsolutePath();
Runtime.getRuntime().exec("cmd /C start " + batchFullPath);
} else if (SystemUtils.IS_OS_LINUX) {
// run linux script
String scriptFullPath = new File("~/myScriptFile.sh").getAbsolutePath();
File workingDir = new File("~");
Runtime.getRuntime().exec("/usr/bin/xterm " + scriptFullPath, null, workingDir);
} else {
throw new RuntimeException("Unsupported Operating System");
}
(Using xterm as it is fairly safe to assume every Linux machine has it installed)
try{
//String[] cmd = new String[]{"/bin/sh", "send.sh"};
//Process pr = Runtime.getRuntime().exec(cmd); //nothing happens
//Process p = Runtime.getRuntime().exec("send.sh"); //File not found
//Process p = Runtime.getRuntime().exec("bash send.sh"); //nothing happens
// ProcessBuilder pb = new ProcessBuilder("bash","send.sh");
// Process p = pb.start(); //nothing happens
}
catch(Throwable t)
{
t.printStackTrace();
}
With this code I am trying to start a simple bash file which is located in the directory of the program. The code of the bash file works when I start it with shell or by simply executing it. The code of the bash file works.
I've tried every option but they are all not working. I've commented what happens in each case. I don't understand that it don't find the file because the bash file is located in the same directory.
You don't see an output for two reasons:
You don't wait for a process to finish
You don't redirect it's output to the same console that your Java process runs
And, probably, you need to use a command like /bin/bash -c path/to/your/file.sh. Note that -c flag.
IMHO, the best way to craft and execute external processes in Java is java.lang.ProcessBuilder.
Supposing that you have your sh file somewhere the in resources directory, here is an example main class:
public class App {
public static void main(String[] args) throws Exception {
final ProcessBuilder processBuilder = new ProcessBuilder("/bin/bash", "-c", App.class.getResource("/46964369.sh").getPath());
processBuilder.redirectInput(Redirect.INHERIT);
processBuilder.redirectOutput(Redirect.INHERIT);
processBuilder.redirectError(Redirect.INHERIT);
processBuilder.start().waitFor();
}
}
Note that I redirect process's streams with redirect* methods. Redirect.INHERIT redirects stream to the corresponding stream of the JVM instance. It works both for input and output streams. Finally, I am waiting for a process to finish with waitFor() method. In fact, you can do more, like capturing the output into a string, providing input from a string or running the process asynchronously, but this is a minimal example.
If you store your sh file in another place, you must update path-related logic.
Take a look at the complete example here. It's a Gradle project, and you can use ./gradlew run to execute it:
$ ./gradlew run
:compileJava
:processResources
:classes
:run
Hello, world!
BUILD SUCCESSFUL in 4s
3 actionable tasks: 3 executed
In my Java application, I want to run a batch file that calls "scons -Q implicit-deps-changed build\file_load_type export\file_load_type"
It seems that I can't even get my batch file to execute. I'm out of ideas.
This is what I have in Java:
Runtime.
getRuntime().
exec("build.bat", null, new File("."));
Previously, I had a Python Sconscript file that I wanted to run but since that didn't work I decided I would call the script via a batch file but that method has not been successful as of yet.
Batch files are not an executable. They need an application to run them (i.e. cmd).
On UNIX, the script file has shebang (#!) at the start of a file to specify the program that executes it. Double-clicking in Windows is performed by Windows Explorer. CreateProcess does not know anything about that.
Runtime.
getRuntime().
exec("cmd /c start \"\" build.bat");
Note: With the start \"\" command, a separate command window will be opened with a blank title and any output from the batch file will be displayed there. It should also work with just `cmd /c build.bat", in which case the output can be read from the sub-process in Java if desired.
Sometimes the thread execution process time is higher than JVM thread waiting process time, it use to happen when the process you're invoking takes some time to be processed, use the waitFor() command as follows:
try{
Process p = Runtime.getRuntime().exec("file location here, don't forget using / instead of \\ to make it interoperable");
p.waitFor();
}catch( IOException ex ){
//Validate the case the file can't be accesed (not enought permissions)
}catch( InterruptedException ex ){
//Validate the case the process is being stopped by some external situation
}
This way the JVM will stop until the process you're invoking is done before it continue with the thread execution stack.
Runtime runtime = Runtime.getRuntime();
try {
Process p1 = runtime.exec("cmd /c start D:\\temp\\a.bat");
InputStream is = p1.getInputStream();
int i = 0;
while( (i = is.read() ) != -1) {
System.out.print((char)i);
}
} catch(IOException ioException) {
System.out.println(ioException.getMessage() );
}
ProcessBuilder is the Java 5/6 way to run external processes.
To run batch files using java if that's you're talking about...
String path="cmd /c start d:\\sample\\sample.bat";
Runtime rn=Runtime.getRuntime();
Process pr=rn.exec(path);`
This should do it.
The executable used to run batch scripts is cmd.exe which uses the /c flag to specify the name of the batch file to run:
Runtime.getRuntime().exec(new String[]{"cmd.exe", "/c", "build.bat"});
Theoretically you should also be able to run Scons in this manner, though I haven't tested this:
Runtime.getRuntime().exec(new String[]{"scons", "-Q", "implicit-deps-changed", "build\file_load_type", "export\file_load_type"});
EDIT: Amara, you say that this isn't working. The error you listed is the error you'd get when running Java from a Cygwin terminal on a Windows box; is this what you're doing? The problem with that is that Windows and Cygwin have different paths, so the Windows version of Java won't find the scons executable on your Cygwin path. I can explain further if this turns out to be your problem.
Process p = Runtime.getRuntime().exec(
new String[]{"cmd", "/C", "orgreg.bat"},
null,
new File("D://TEST//home//libs//"));
tested with jdk1.5 and jdk1.6
This was working fine for me, hope it helps others too.
to get this i have struggled more days. :(
I had the same issue. However sometimes CMD failed to run my files.
That's why i create a temp.bat on my desktop, next this temp.bat is going to run my file, and next the temp file is going to be deleted.
I know this is a bigger code, however worked for me in 100% when even Runtime.getRuntime().exec() failed.
// creating a string for the Userprofile (either C:\Admin or whatever)
String userprofile = System.getenv("USERPROFILE");
BufferedWriter writer = null;
try {
//create a temporary file
File logFile = new File(userprofile+"\\Desktop\\temp.bat");
writer = new BufferedWriter(new FileWriter(logFile));
// Here comes the lines for the batch file!
// First line is #echo off
// Next line is the directory of our file
// Then we open our file in that directory and exit the cmd
// To seperate each line, please use \r\n
writer.write("cd %ProgramFiles(x86)%\\SOME_FOLDER \r\nstart xyz.bat \r\nexit");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
// Close the writer regardless of what happens...
writer.close();
} catch (Exception e) {
}
}
// running our temp.bat file
Runtime rt = Runtime.getRuntime();
try {
Process pr = rt.exec("cmd /c start \"\" \""+userprofile+"\\Desktop\\temp.bat" );
pr.getOutputStream().close();
} catch (IOException ex) {
Logger.getLogger(MainFrame.class.getName()).log(Level.SEVERE, null, ex);
}
// deleting our temp file
File databl = new File(userprofile+"\\Desktop\\temp.bat");
databl.delete();
The following is working fine:
String path="cmd /c start d:\\sample\\sample.bat";
Runtime rn=Runtime.getRuntime();
Process pr=rn.exec(path);
This code will execute two commands.bat that exist in the path C:/folders/folder.
Runtime.getRuntime().exec("cd C:/folders/folder & call commands.bat");
import java.io.IOException;
public class TestBatch {
public static void main(String[] args) {
{
try {
String[] command = {"cmd.exe", "/C", "Start", "C:\\temp\\runtest.bat"};
Process p = Runtime.getRuntime().exec(command);
} catch (IOException ex) {
}
}
}
}
To expand on #Isha's anwser you could just do the following to get the returned output (post-facto not in rea-ltime) of the script that was run:
try {
Process process = Runtime.getRuntime().exec("cmd /c start D:\\temp\\a.bat");
System.out.println(process.getText());
} catch(IOException e) {
e.printStackTrace();
}
I use the following to launch a Java application from another Java app.
ProcessBuilder pb = new ProcessBuilder(javaPath + javaCommand, maxMemStr,
minMemStr, stackSizeStr, jarCommand, jarfile, jarArg);
try {
Process p = pb.start();
} catch (IOException ex) {
Logger.getLogger(launch.class.getName()).log(Level.SEVERE, null, ex);
}
where javaCommand is either java or javaw (javaPath is empty most of the time unless a user points to an alternate path). The problem is, after the app launches, even when I verify the process list to contain java, it doesn't show the console.
Is it because PrcoessBuilder doesn't invoke the command shell? Is there a way to show the console programatically?
Thanks in advance.
This is because the "command console" itself is a process that attaches to the std-in/-out/-err streams of another process and displays them on the screen. When you launch Java all by itself, no other processes will be handling those streams, hence the lack of a command console. To get the results you want, you will need to launch a new instance of the command console and subsequently have it run your custom java command.
There may be a better way to do this... but I think the solution to this is going to be platform-dependent. In Windows, you could do something like:
ProcessBuilder pb = new ProcessBuilder("start", "\"JAwesomeSauce\"", "cmd.exe",
"/k", javaPath + javaCommand, maxMemStr, minMemStr, stackSizeStr, jarCommand,
jarfile, jarArg);
try {
Process p = pb.start();
} catch (IOException ex) {
Logger.getLogger(launch.class.getName()).log(Level.SEVERE, null, ex);
}
I assume you could do something similar in Linux/Mac if that's the O/S you're using.
You may want to run the command like this:
cmd /K java ...
or
cmd /C java ...
As far as I remember the Processbuilder opens a pipe to a specific process.
Your command window is a process itself with all you see. If you enter commands the cmd/bash usually creates new processes and attaches to them.
Destroying spawned ant process, from windows, does not work. Unix variants this works fine but from windows this does not work. Code snippet is below. While the return code is correct (1) the spawned process continues to execute until done. Only a problem on a windows. Any ideas?
ProcessBuilder build = new ProcessBuilder();
List<String> list = build.command();
list.add("cmd");
list.add("/C");
list.add("ant");
list.add("-f");
list.add("HelloWorld.xml");
try {
Process p = build.start();
Thread.sleep(5000);
p.destroy();
int i = p.waitFor();
System.out.println(i);
} catch (Exception e) {
System.out.println(e);
}
The problem is that Process.destroy doesn't kill the process grandchildren. There is a bug opened for it since 2002.
Anyway, why are you spawning a new prompt with cmd /c start to call Ant? If that is not a requirement just call ant.bat -f HelloWorld.xml.
UPDATE
ant.bat will also spawn children processes. There is a workaround with taskkill that may help.
Problem solved by using a mix of wmic (to grab the windows process list) and taskkill (to force kill the running process).