Develop Reference

Running Java program in a Docker Image

So I have a Docker network that has a Docker file with a bunch of information. I have a java program that is going to bring up the enviorment and then produce several commands to run within this enviorment. To be clear, the first command I need to run is NOT inside the Docker enviorment. I am having some challenges with the Process and Runtime classes.
First, say I wanted my java program to launch a new gnome terminal and then run a command to get into the docker network. I have this command,
Process process = Runtime.getRuntime().exec(new String[]{"gnome-terminal"});
Gnome terminal sucessfully comes up but any additional arguments I give in this array are just ignored. For example,
Process process = Runtime.getRuntime().exec(new String[]{"gnome-terminal","ls"});
Does not work. The command I ultimatly want to run would look something like this,
Process process = Runtime.getRuntime().exec(new String[]{"gnome-terminal","sudo","docker","exec","-it","sawtooth-shell-default", "bash"});
Second, Once I have this running, will additional commmands I run work within the Docker enviorment? I have a python file with a Stream handler that specifies the correct commands to run.
Other documentation on related issues was limited.
I made sure my code was wrapped in a runtime exception try catch and that I was running the correct .class file. Any help on this would be great!
Edit: I have also tried to run this in another linux terminal like Hyper and Tilda
I also am able to get a sudo sign in when I run the command like so,
Process process = Runtime.getRuntime().exec(new String[]{"gnome-terminal","--","sudo","docker","exec","-it","sawtooth-shell-default", "bash"});
However it closes immediatly after authorizing.

Okay this is what I was attempting to do.
https://www.atlassian.com/blog/software-teams/deploy-java-apps-with-docker-awesome
This site is outdated and I had to use this link for getting that latest version of the java PPA.
This process basically installs java into the docker contatiner so that I can run a java program that uses Runtime.

Runtime.getRuntime().exec() doesn't execute some commands

I'm beginner at java and have some problems. I've read several topics about this theme but none of them worked for me. Here is my code:
try
{
Console console = System.console();
String command;
while(true)
{
command = console.readLine("Enter input:");
Process proc = Runtime.getRuntime().exec(command);
// Read the output
BufferedReader reader =
new BufferedReader(new InputStreamReader(proc.getInputStream()));
String line = "";
while((line = reader.readLine()) != null) {
System.out.print(line + "\n");
}
proc.waitFor();
}
}
catch(Exception e) {}
So what I'm trying is to make a java program and run terminal commands in it(I'm using linux). This program works with commands like "ls" "ps ef" and others but it doesn't work when I type "cd". I know that cd makes different process and should be used this way: "Runtime.exec(String command, String[] envp, File dir)". My questions is:
How to make my program run all kinds of terminal commands? Sorry if question sound silly. Thank you.

The cd command is a shell built-in command. There is no shell when you run a command via exec(...). Indeed, if you try to find a cd command in any of your system's bin directories, you won't find one ... because it is impossible to implement as a regular command.
If you are trying to use cd to change the current directory for the JVM itself, that won't work because a command can only change the current directory of itself and (after that) commands that it launches itself. It can't change its parent processes current directory.
If you are trying to use cd to change the current directory for subsequent commands, that won't work either. The context in which you set the current directory ends when the command finishes.
In fact, the right way to change the directory for a command run using exec is to set it via the ProcessBuilder API itself.
How to make my program run all kinds of terminal commands?
You can't. Some of the "terminal commands" only make sense as shell commands, and that means you need a shell.
I suppose, you could consider emulating the required behaviour in your Java code. That would work for cd ... but other commands are likely to be more difficult to cope with.
(For what it is worth, it is possible to implement a POSIX compatible shell in Java. It is just a LOT of work.)

you've actually got to run the console you want to use (ie sh, csh, bash, etc) and then use the process OutputStream to feed in commands

I think the Problem is not your Code, the command is the problem...
what do you want to see if your command is cd ??
In Background it changes the path but you get nothing back.
Changing the Directory is not processing any output.

This worked for me:
Runtime.getRuntime().exec(new String[]{ "/system/bin/sh", "-c", "ls -l" } );

Permission denied error in Java for chmod command

I have an executable file (ffmpeg) that I'm trying to run with a Java program on a Mac. I used the Java program to send the command chmod 777 /path/to/ffmpeg, but when I try to run ffmpeg, I get the following error:
java.io.IOException: Cannot run program "/Users/james/WalkTheHall/ffmpeg": error=13, Permission denied
But when I run chmod 777 /path/to/ffmpeg from Terminal on my own before opening the Java application, the command to ffmpeg will run just fine in the Java program.
Is there a difference between calling chmod from within the Java program and calling it on my own? Why will it not work? Thank you!

I just had the same problem in my code.
i solved this by add waitFor after exec. The "chmod" process is not finished when next command is executed. the code may look like:
p = Runtime.getRuntime.exec("chmod 777 xxx");
p.waitFor();
Runtime.getRuntime.exec("./xxx");

I'd guess that chmod is a shell command, not an executable. Try running chmod through your shell. See more details here: Want to invoke a linux shell command from Java

Yes, there is a difference. When you run the command from the terminal, it is you who is performing the action, and thus it is performed using your credentials. The Java application is running the command using the Java application's permissions. This is to prevent an application from running and then making dangerous, unwanted changes to the file system. Perhaps someone else can elaborate and give guidance to a workaround for this.

I am currently working on a project that also makes use of FFMpeg on OSX. I store FFMpeg in the JAR and extract it and set executable on use as you seem to be doing. This is what I do, and it seems to work.
public static void setExecutable(File file, boolean executable)
{
Process p = Runtime.getRuntime().exec(new String[] {
"chmod",
"u"+(executable?'+':'-')+"x",
file.getAbsolutePath(),
});
// do stuff to make sure p finishes & capture output
}
The code is GPL, so feel free to check it out. Its not the nicest codebase, and even the FFMpeg stuff is perhaps overly complex, but it works.
Source is viewable at http://korsakow.net
These two files in particular might be interesting for you
FFMpegEncoderOSX.java
FileUtil.java

Try this:
File commandFile = new File("myFile.txt");
commandFile.setExecutable(true);
Process p = Runtime.getRuntime.exec(commandFile.getAbsoluteFile());

to start an program on OSX you need this:
Runtime.getRuntime().exec("chmod 777 "+path); //in order to execute it
Runtime.getRuntime().exec(path); //execute it
Runtime.getRuntime().exec("chmod 744 "+path); //undo every change
path should be the path to the exc of the program, for example:
AppStore -> Applications/App\ Store.app/Contents/MacOS/App\ Store

Java ProcessBuilder showing console of started java application?

I have a JAVA application that launches (using ProcessBuilder) another JAVA application like this:
String val = "something";
ProcessBuilder processBuilder = new ProcessBuilder("java", "-classpath", dir, appName, val);
Process p = processBuilder.start();
Now, this works fine, appName is launched with the parameter val and it runs and works ... great ... the problem is no Console Window appears ... appName does a LOT of outputting to the console and we need to see it ... how can I start the process with a console?
I am trying stuff like ("CMD.exe", "java", "-classpath", dir, appName, val), etc... but I can't get it right ...
Also, I can't redirect the streams, my program can actually start 5-10 of these appName's, each should have their own console window showing their own information.
Any help would be much appreciated.
Thanks,

console windows are generally not the most reliable form of logging. they only store a set amount of information (buffer) and can behave differently across platforms.
i strongly suggest logging to a file using something like log4j and if you need to see it real time use a tail like program (i see you're using windows).
in addition to this, seeing as you want the windows visible at all times and launching a tail program for each log might be annoying, i'd write my own log window in java swing.
the basic idea is to not rely on the OS too much.

Tried Runtime.getRuntime().exec("cscript java -classpath ..."); ?
Anyway, consider using a logging framwork (log4j, commons-logging), because opening 5 consoles is not the most clever thing to do.

I call a few shell scripts via Process to open a command line window and launch whatever I need. As long as the scripts don't detach - you can usually stop any shell command from doing this -java will still hold the running process.
I did it in linux but the concept should be similar.
#!/bin/bash
# To open a process in a new window.
gnome-terminal -x ./your-real-shell-script-here.sh "$#"
the real script will have your java execution in it, such as:
#!/bin/bash
java -jar your-jar-file.jar "$#"
I think you can use javaw to run on windows, so you might only need the one shell script.

A Console object only exists when you execute java.... from a console. Otherwise, the call to obtain one returns null.
If you want to see a console, you need to open a command shell console (e.g. windows cmd.exe or Unix bash shell window) and type:
java -classpath="..." com.example.appName arg1
If you want to run in a different manner, sorry to say, logging to Console is not for you. Instead, log using one of:
log4j
slf4j
logback

Launching jEdit From Java Swing App Using Runtime.getRuntime().exec()

I'm writing a Java Swing Application running on Red Hat Enterprise Linux 5 server that I would like to launch jEdit to view log files.
Here is some example code.
public static void main(String[] args) throws IOException, InterruptedException {
String cmd = "sh -c \"java -jar /tmp/jEdit/jedit.jar /tmp/test.txt\"";
System.out.println(cmd);
Runtime.getRuntime().exec(cmd);
}
The output is:
sh -c "java -jar /tmp/jEdit/jedit.jar /tmp/test.txt"
If I copy and paste the cmd output in a terminal window, it runs fine.
I have tried a bunch of cmd values, but I can never get the jEdit window to be visible.
With changes, this process works fine on Windows.
Is what I'm doing possible on Linux?
Thanks in advance!

As jEdit is implemented in Java, perhaps it would be easier to check the source for what the main method (in the class declared in the manifest file included in the jedit.jar) does and do the same thing without using Runtime.getRuntime().exec() at all.
If you do want to stick with it, you could try passing the individual commands as an array to exec(), this often solved such problems for me.

Linux uses the concept of display ports for its X-Windows system. This allows it to maintain a different desktop environment for each user. It also allows a user on remote machine to run a desktop app from the first machine but see the UI on the remote.
Windows, having only one available desktop environment at a time, does not.
First thing you definitely have to do is add the environment variable "DISPLAY=localhost:0" to the environment from which you are launching this. However, you may also need to run 'xhost +localhost' or this may not be allowed.
Double-check, too, that you didn't successfully launch a bunch of jEdit processes that are now zombies (using top) and kill them if necessary (using kill).

Runtime.exec() needs some special attention. The exec method that accepts a String uses the space character as a delimiter to break up the string into commands. You need to use the exec method that accepts a String[]. Read more here, specifically near the bottom.

I´ve done this once and I got the same problem
What I've done is to write the command line into a text file and then execute the text file as a shell script file.
It worked fine for me.

Jedit has a launcher script, /usr/bin/jedit I guess. Simply typing jedit in command prompt runs it, at least in current version, 4.5. Try that script instead of explicit java command.