I'm running Xorg and my (Qt) program daemonises itself. Now I log out and restart the X server. When I log in again my process is still running fine, but I can't see it.
Is there a way of attatching the new incarnation of the X server to the old process?
If I don't restart the whole server, but log out and in again, is there a way to look at the old process?
Thanks
xpra should achieve your requirement. And it can also start tcp connection (without need of ssh). Start it on the you server:
xpra start :100 --start-child=xterm --bind-tcp=0.0.0.0:10000
Connect it on your client:
xpra attach tcp:SERVERHOST:10000
You can also use mac or windows xpra app to connect it. I tried in on win7 and osx10.10.2. The download link:
windows: https://www.xpra.org/dists/windows/Xpra_Setup.exe
mac: https://www.xpra.org/dists/osx/x86/Xpra.dmg
After the connection to the X server is lost, it is not possible to regain it.
There was an xserver proxy called xmove, but it is quite deprecated and doesn't work with several newer X extension, which are likely used by modern toolkits.
You could try to run your process in another virtual X server like xvnc or (better) NX. NX is a X proxy technology developed by NoMachine. There exist free implementations of NX servers as well.
If you run your program inside such a server, it is possible to attach and detach from it from arbitrary graphical environments.
Use something like Xpra: it allows you to run applications on an off-screen X11 server to which you can re-attach whenever needed, and from remote machines too. It supports "seamless" sessions too so the windows will appear just like local windows.
Practical example:
xpra start :10 --start-child=/bin/YOURAPP
Then whenever you want to re-attach (say after an X11 server restart):
xpra attach :10
Or from a remote machine:
xpra attach ssh://THESERVERHOSTNAMEORIP/10
Related
In my University we writing in server is located in University(we have acces via ssh).
I use Ubuntu on my laptop so I have the same program like on server.
At home I have low speed internet and when i want to send program by X server it take some time to run it. Is some way to start program for example emacs from my computer(it starts immediatly) and recive only data from server?
In general, you might use sshfs or similar to mount a remote filesystem so that your local applications can access the files. SSH port forwarding may be useful if you need access to more than just files.
For Emacs specifically (it's not clear whether this is the only use-case for your question) you can either:
a) ssh into the remote host, and run emacs -nw to run a remote instance of emacs in your terminal. This is vastly more network-efficient than running a remote GUI emacs with a local X display. This approach is also good if you already have a running Emacs server on that remote host, as you can connect to it efficiently with emacsclient -nw
b) Start a local emacs instance and use the standard tramp library to access the remote files.
e.g. C-xC-f /ssh:you#hostname:/path/to/file RET
Tramp is excellent, so you should spend some time reading about it.
See C-hig (tramp) Usage RET
Is it possible to clone image from display via ssh? I want to see what is on my first laptop display from another laptop, but without any additional software like teamviewer or vnc.
The short answer is: Yes, but you may be unhappy with the results.
The protocol you are looking for is called X11 Forwarding. This option must be enabled on your server by setting X11Forwarding yes in /etc/ssh/sshd_config, then reloading the daemon.
Once enabled on the server, the client must initiate their ssh session using the -x flag.
The major limitations of this technology are that:
The data is not optimized for transfer over the wire. For most environments you end up with a low framerate and/or graphical artifacts. As long as you're doing something like running a GUI installer it should not be a problem, but do not expect to be able to stream video / play a game using X11 forwarding.
The client must have an X server installed. If you are connecting from a Windows machine (or another machine that does not have an X server installed), you may need to use a project such as Xming in order to actually interpret the data once you get it to the client.
I would like to setup a small computer (Raspberry Pi) running Arch Linux to accept remote X sessions. Doing this usually means setting up Xorg server and running one of the Display Managers. I have done this before, and I will go this route if I have to. However, since the machine is very underpowered, and it is actually not connected to a physical monitor, I was hoping to setup the X server to accept only remote sessions. This way no memory would be wasted on managing the local graphics card, video memory etc, since they are not being used. Is it possible to setup the X server to accept only remote sessions without going into local graphical mode? And how?
It's possible to set up a *ix to remote display to a system you're sitting in front of, without an X server on the machine running the app.
You need X11 libraries, one or more X11 applications, and you probably want openssh set up for remote X11 forwarding - all on the raspberry pi. You'll also want an X server running on the machine you're sitting in front of.
On the Raspberry Pi, change your sshd_config to include "X11Forwarding yes". After making this change, restart sshd or reboot.
Then apt-get or yum your X11 libraries and app(s).
When you connect to the Raspberry Pi machine, use "ssh -Y" instead of just ssh to pass along xauth data.
Good luck!
Disable automatic start of the login manager and X server, instructions are googlable, say http://www.debianadmin.com/howto-boot-debian-in-text-mode-instead-of-graphical-mode-gui.html. From personal experience running X apps on raspberry remotely is not too good either.
I am having some problems with launching firefox from a Linux daemon written in C.
When I launch firefox on the machine itself (via terminal) from the command shell using /usr/bin/firefox it works OK and a firefox browser window lanunches as it should.
However if I try this within my C daemon using system("/usr/bin/firefox"), firefox launches its process in the terminal but the browser window is not opened?
A similar thing happens when I try to do this using remote terminal acces. It's something to do with telling the system to open firefox in window mode rather than trying to open it in terminal mode - but I dont know how to specify this using bash commands?
I am using Lubuntu 11.10 in my Linux System.
Any help is most appreciated.
There's a reason I asked why you're attempting to do what you want. I didn't want to get into great details in my comment.
Firefox on Unix is an X-Window process (most of the Linux/Unix desktops are based upon the X11 protocol which is the heart of X-Window). What X-Window does is separate the display of the program from the process running the program. For example, I am now running Firefox from a Linux box at work, but the Linux box is actually displaying the Firefox browser window at home on my Mac.
In order to do this, I had to:
Run X11 on my Mac. The X11 program creates a default X11 client display called 0.0 which pretty much says the first screen and the first instance of X11 running (computer geeks like counting from zero). The process runs in the background on my Mac. In a certain sense, it's really a server process and not a client because it's waiting on port 6000 for a client X11 process (Firefox) to tell it what to do.
Before I run firefox, I have to tell my Mac's X11 process that I grant the X11 server running Firefox to be able to display on my X11 client process. Otherwise, you can imagine someone spamming another person by continuously popping up Windows on their display. You can use the xhost program to do this.
In order to run Firefox on the Linux box, I have tell the Firefox process what X11 client I'm running it on. I can do this by setting the DISPLAY environment variable to something like "10.0.1.33:0.0". This means the X11 client is running the the machine on IP address 10.0.1.33, and I want you to use the first screen, and the first instance of the X11 client on that screen.
Now, I can run Firefox on my Linux box, and the display will display on my Mac.
The problem you're running into is that there's simply no X11 client when you're starting FireFox as a daemon process. An X11 client is associated with a user and a display of some sort. The display could be a virtual display, but there's got to be an X11 client that's running and is addressable in some way, so the process knows where to display the output.
By the way, you said daemon which has a very, very specific meaning in Unix/Linux. A daemon is a process that runs in the background and usually has a service (and a port) associated with it. For example, there's an FTP daemon called ftpd, the mail server uses the sendmail daemon, ssh has the sshd daemon. Daemons have no display associated with them.
However, it looks like you might be using the word to mean launching Firefox via another process. Is that true? If so, you'll have to make sure that Firefox knows the X11 display to use (there's a command line setting to use to specify the display), and that your X11 client (your login session) has given permission for another process to update your display with the program window.
Can you please explain what you're trying to do in a bit more detail? If you simply want to download a file from a remote http server (which of course is running the http daemon process called httpd), you should use curl or wget which don't require a display and are way simpler to use. If you're trying to do something else, let us know exactly what it is.
Firefox needs to know which display it should open on. When you run it from within a gui, even through a terminal emulator, the DISPLAY environment variable is set to the appropriate value. When you launch from the daemon, try system("/usr/bin/firefox -display=:0").
Make sure that the DISPLAY environment variable is properly set in your daemon to refer to the X server that you want your firefox to use.
If the daemon is run as a different user account than the user account that "owns" the X server that you want to use, you will also need to use xauth(1) to configure the authentication token to grant permission to use the X server.
Often times, it is far easier to use ssh -X to tunnel X and properly configure the xauth(1) tokens in one go than try to manage xauth(1) tokens yourself. Maybe adding ssh -X into your environment would be suitable, maybe not. (I've even used ssh -X root#localhost before when I needed to run an X client as root and didn't want to bother with configuring xauth(1) manually. ssh(1) is just so much easier.)
I do this all the time using VNC and it is very easy, but I am curious about a few things like XDMCP. As I understand it, this is a way of creating the entire desktop on a remote X-Server which seems fairly elegant.
Several years ago, I worked on a Solaris server and multiple developers had X-Servers running in Windows and we were able to access a full remote X-desktop. All my efforts so far in X based systems seem to indicate that only one instance, remote or local, of the desktop can be loaded, so I guess this Solaris thing was an actual application that "emulated" a desktop, but who knows....
Any input ?
From Windows I've found the best way to do this is using the Xwin command in cygwin.
Steps:
Install Cygwin, making sure to install X11. (Do this by scrolling to the bottom of the list on the "select packages" screen and click on the word "default" to the right of "X11". Give it a second or two and it will change to "install".)
Then, just run the Xwin command like this:
Xwin -query your.unix.system.name
You'll get a full-screen login window from you unix box. That's it!
Btw, sometimes firewalls get in the way of the UDP protocol for XDMCP. If that happens, look up the port numbers (one UDP outgoing, and one TCP incomming) and unblock them. Other xdmcp troubleshooting tips here.
NX will allow you to use a complete remote desktop environment locally, and most Linux distros already have the server available.
As an alternative to full cygwin install you might want to look at Xming. It is quite a bit lighter and should provide the same functionality.
In Xorg/GDM/LightDM options : "listen" should be activated (disabled by default)
In windows, try Xwin32.
In Linux, try Xnest (windowed) or X with "-query" command.
Be careful: it's slow and everything (passwords included) is transmitted in clear. So keep it on local network, tunnel it in SSH or better don't use it.
I found an additional remote desktop implementation which works quite nicely with LXDE:
x2go
Has clients for Windows, Linux and MacOS X.