How does one start a Java server in Linux via console? - java

So I have a Java program sitting on my DigitalOcean server and I have been using the command,
java -jar IO_Server.jar
To run it. However the problem is that when I type this command in PuTTy, it requires that I keep PuTTy open. If I close PuTTy, the server then shuts down which is not what I want. I need a way to start the server and leave it running even after PuTTy is closed.
I have been trawling the internet for about 2 hours without any luck. I keep coming across the aforementioned command. I have used the command before but I cannot remember what it is nor where I found it.
Help would be appreciated!

You can use nohup. Something like
nohup java -jar IO_Server.jar &
The first line of the linked Wikipedia article says
nohup is a POSIX command to ignore the HUP (hangup) signal.

To add to Elliott's solution, another option is to use screen which allows you to open a "new window" run a command and detach from that window. Then, even when you're logged off, the command is still running, and you can re-connect via ssh and re-attach to that window and continue from where you stopped.
Here's a "getting started guide" to screen.

Related

How to move Java runtime console to different terminal window?

I executed a Java program from the command line in terminal app A. I want to move the console to terminal app B without having to exit and re-execute the program.
I can think of a few potential ways to solve this, ranging from:
A) In Java implement a new InputStream and OutputStream that somehow can be wired to a new process started in terminal app B.
...to
B) Find a way to put the main Java process in terminal app A in the "background" so that original process can be reopened in a terminal app B.
Ideally, I want to be able to "log in to" and "log out of" my Java process from any terminal on my computer. Has anything like this already been accomplished, and which approach would be best to make it myself? I am open to solutions that involve Java code, shell scripts, or both.
My specs:
OSX: 10.12.4
Usually running zsh on iTerm
If I was using Linux, the perfect solution would be reptyr, a command line tool that allows you to easily switch terminal windows.
On Mac, the best solution I have found is screen. It can also be used to switch terminal windows but must be invoked before running java in order to work and seems a lot more complex.

cmd control command recognition in java

I am just wondering if there is a way, after launching "control wuaucpl.cpl" from my java script, to recognize if it has ran, or if it was blocked via active directory, or security settings. I have tried launching it with error streams, but so far I haven't seen any way of actually telling if it has opened up and ran or not. With similar tests I would just run a tasklist and check there to see if the process was running, but of course it comes up under explorer.exe and hence, would be impossible to tell.
EDIT:
This can also apply for any cmd control commands. EG: "control desk.cpl" or "control appwiz.cpl"
Any help would be greatly appreciated !
Thanks.

Windows: Running privileged command from non-privileged using CMD (or Java)

I will have a service that runs as administrator and listens on a port. My GUI program will talk to the administrator service for the items that require administrator privileges.
If the service is not yet running, I will need to start it. How can I get my GUI program to run a command as administrator? I assume the user will be asked if they want to continue.
I am hoping there is something I could type in a CMD window because that should fit very well into my Java program. I am thinking something like run-as-admin javaw my-service.jar where run-as-admin is the command that asks whether to continue or not.
Windows contains the tool "runas" which can be used to start any executable with a different user account.
On the commandline you would then use:
runas /user:Administrator "javaw -jar my-service.jar"
The only drawback is, that you need to type in the password, you cannot supply the password as an argument to the runas command
You have a problem here. Non admin processes cannot start services. The very simplest thing to do is to arrange that the service starts automatically. I'd strongly recommend you take that route.
What you are thinking of doing would involve creating a helper application that includes the UAC manifest with requestedExecutionLevel set to requireAdministrator. This helper app could then start the service. The problem with this is that it requires that the logged on user is in the administrators group which you cannot guarantee will be the case.
All in all, starting the service automatically is to be preferred.
You can't execute a batch file as administrator. You need to create a shortcut to that file and then set the flag in the Shortcut 'Execute as Administrator', if this is really what you want to do.
To do this from the desktop, select the Shortcut, right click and Properties->Shortcut tab->Advanced button. Then check Execute as Administrator checkbox.
To do this programmatically, see How to set "Run as administrator" flag on shortcut created by MSI installer
We use the Wrapper library for this:
http://sourceforge.net/projects/wrapper/
The official website seems to be suffering from dynamic dns issues at the moment, so here is the wayback archive version.
From the command line (and by extension, Java) you can install, uninstall, start, and stop your Java application as a service.

How to run multiple simultaneous bash shells without a GUI?

Is it possible to have several command prompts running simultaneously and switch between them, without using a GUI?
Background
I have installed CentOS-5.5-i386 without any extras, so I have a bash command prompt with root access but no GUI as far as I know.
I have written a simple Java servlet using Jetty. When I run it, it gets to a couple of commands like this;
server.start();
server.join();
where it waits for incoming requests forever - ie. it never returns to the command prompt.
I want to run a web server without the overhead of a GUI. How can I run my Java program and also continue to use the server from a command prompt?
I apologise for the waffly nature of this question but I am both a Linux newbie and a Java newbie.
Regards,
Nigel
In the general case you want screen or tmux. For running daemons, though, take a look at nohup my-daemon & or even just my-daemon &.
You can switch between consoles using Alt+F1 to Alt+F6. For more shortcuts take a look here: http://linux.about.com/od/linux101/l/blnewbie5_1.htm

Running Java UI program though unix

I want to facilate my client to run java program through UNIX command prompt using some shells. It'll look more effecient if they would be able to give input through some GUI. So it can be tested immedietely. I dont want prefer unix commands fro input.
Can somebody tell me how to run Java swing or applet programs in UNIX?
As Thompson mentioned, looking at Java Web Start could be a good idea.
Otherwise, if what you want is to execute, using a *NIX-like terminal, an application located on a remote host and have it rendered on your local display, then you need to do a few things:
you need a working X server on the local machine
you need to export the DISPLAY to the local machine (you can do this by setting up the DISPLAY environment variable on the remote system)
then you need to start your Java app from the command-line.
Hope this helps.
Here's an example of how to export your display over SSH.
Java programs use the X windows system (just like any other GUI on Unix). Assuming your X windows system is setup correctly, you should just open up a JFrame and do your GUI coding just like Windows.
Using the command prompt to launch a GUI is so last millennium. If you can distribute from a server, look into Java Web Start to provide the end-user with a simple and painless install.
Oh, and of course, follow Starkey's advice to throw a JFrame into the mix.
If you have an X-server installed locally, Putty can tunnel the X11-graphics generated by Linux Java back from the server to your local machine, and view it there.
If the above doesn't make sense to you, your next best bet is either running the Java code locally with Java Web Start (and code it to communicate back to the remote server) or run Servlets inside a Java Web Server running on the remote host.
In other words, GUI over a Putty connection is not something which is easily done.

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