Is there a way to keep my Linux services running after I close the bash prompt? I had hoped that this would be a little more robust than it actually is. When I close bash on Windows 10 everything shuts down, which I should have expected of course.
This is not currently possible, but Microsoft is aware of it and may add that functionality in future.
Related
I'd like to use terminal for all of my normal git and compiling and running processes (my school has a server that is linked to my repo on bitbucket), but I really don't like terminal-based text editing software such as Emacs and Vim. Is it possible to open and edit files from the terminal using a GUI based text editor? The reason I'm asking is because the terminal is the only way I can access the server files. Thanks in advance!
Aw, but vim is the best! :) Well, you can use nano, which is friendlier. Or, if you insist: if you are using SSH to connect to the server (and the server has an X server running !) then you can look into the ssh -X option to view X windows on your remote machine.
Oh and you could look into scp command as well (behaves almost just like regular cp, but the destination is on another host). That way you could edit on your machine, then copy it via SSH (although you'd want to be careful when copying files directly to the server filesystem)
Edit: Also, if you really don't like using the terminal (why though? (-: ), some file managers allow you to get the same functionality of the previous commands purely via GUI (for example).
You've left out some important information that someone would need to know to answer your questions. The other posters have made some assumptions.
You've mentioned this "terminal", but it's not clear exactly what that is, or how you're getting to it. What kind of computer do you have in front of you? What shell is running in that terminal? Is the shell running on your local computer, or have you remotely connected to a server and running that shell on the remote computer?
Based on what you said, I have a feeling you're making a remote connection to a server, perhaps using ssh. You likely have either a Windows or Mac PC in front of you. In those circumstances, running a GUI editor like Eclipse is possible, but likely not practical. You would have to have Eclipse installed on that remote computer, and you would be displaying the Eclipse window on your local computer using the X11 protocol. That takes a lot of bandwidth.
If my assumptions are correct, my recommendations depend on how long you expect you're going to want to stay familiar with this environment. If you intend to do this sort of work forever, then you should learn vi and Emacs to the best of your ability. As someone who's been using Emacs likely longer than you've been alive, I'd recommend you learn it, but vi is also a critical skill.
UNIXY systems provide open or gopen, depending on your OS, that should get the job done. From the man page:
By default, gopen will open filename with the application currently assigned to the file's extension. But by specifing the -a flag on the command line you can tell gopen to open the file with another application.
This means that you can use it to open files in your preferred editor
with a line like
gopen -a Eclipse file
I need to open a lightweight X server in C language. I figure vnc may be lightweight enough and universal in all Linux flavor and windows. Is there a C API to start vnc server? What libraries does it need?
If you know the name of the binary (executable) that you want to start, you can probably just use system() to start it. Assuming the binary is in /usr/bin/vncserver:
system("/usr/bin/vncserver");
Note though, as pointed out in a comment, that your question is fairly confused. A VNC server is not an X server. It's perfectly possible to run a VNC server without running X "inside" it. So starting a VNC server will most likely not help with your problem. I suggest you post a new question with a more clear description of what you're trying to achieve, this sounds a lot like you're "jumping" to a solution.
I have to call several (> 10) .exe command line programs in the background.
Creating a Windows Services doesn't sound very appealling in this context - c'mon, that's a bit overpowered for such a simple task.
Is there anything like a daemon(3) subroutine for Windows?
You might look into using the srvany.exe service wrapper found in the Windows Server 2003 Resource Kit Tools. I have used this method quite successfully under Windows XP, but I cannot comment on how it may work for newer versions of the OS.
There seems to be plenty of information available1 on how to use this tool.
1 - Google search for srvany+howto
How exactly would one go about getting an OpenGL app to run fullscreen straight from the terminal (Ubuntu Server 9.04)? I've developed an application for visual diagnostics on my server, but, I'm not totally sure the best way to get it to run in a windowless environment.
Ideally, I would run my program:
./visualdiagnostics
and have that launch the OpenGL app. Then, via a simple Ctrl+X key binding, I'll kill the app and go back to the terminal.
Do I need to install X11 and then somehow launch it from within the program? What would be the best way to detect if it's already running and, start/stop it if necessary?
And FYI: No, I'm not trying to get this to run over Putty or anything... I have a monitor hooked straight up to the server. The server has proper video drivers installed.
There are several parts to your task. Keep in mind that some of this can be very distro-specific; but since you said Ubuntu we'll talk Ubuntu!
Also you tagged this question C however I am starting off with a common Linux pattern: a native application with a Bash shell script wrapper. Perhaps once you get things working well you might fold that functionality into C if you have to.
Detecting whether X is running
Being root can help a lot. Some things that work.
pgrep Xorg
Check whether /var/lib/gdm/:0.Xauth exists. This will be there even if nobody has logged in but GDM is running.
ls -l /home/*/.Xauthority (Even if you're not root you can at least confirm whether you are running X.
Piggybacking an existing X session
You did not specifically mention it but if you are root at the console, or if you want to run the app as the same user who is already logged in, it's pretty easy.
You have to get the DISPLAY and XAUTHORITY environment variables right, and once you do you can use the existing X display.
For DISPLAY you might just assume :0 or you could find an existing X program (x-session-manager is the GNOME standard) and read its environment from /proc/PID/environ. Variables are in key=value format delimited by a null byte. For example, if its PID is 12345:
cat /proc/12345/environ \
| ruby -ne 'puts $_.split("\0").select {|e| e.starts_with? "DISPLAY=" }'
For XAUTHORITY you could get it the same way. Or if you prefer guessing, it's almost always /home/whoever/.Xauthority
Once you have those two variables, running X code is easy, for example:
env DISPLAY=:0 XAUTHORITY=/home/brian/.Xauthority ./visualdiagnostics
Stopping X
This one is easy if you're root: /etc/init.d/gdm stop. killall Xorg will work too.
If you are a user, kill your own Xorg or x-session-manager process. (I'd welcome input from others for the canonical way to do this. Maybe some dbus-send message?)
Starting X
I would recommend xinit whose goal in life is to fire X and run exactly one program.
For example: xinit ./visualdiagnostics
You can also tell xinit what resolution to run X at which may or may not be important to you. (This becomes important in the full-screen section below.)
The problem with this is you will have no window manager— no maximize and minimize buttons. It's not just cosmetic. Usually an app is useless because a popup window cannot be moved or you cannot focus on the right input field. However if you have a special app it could be sufficient (see full-screen below).
The next step would be my answer to everything: another shell script wrapper! Something simple that starts the window manager and then becomes your program should work.
#!/bin/bash
#
# Start visualdiagnostics once xinit calls me.
/usr/bin/metacity& # Or ratpoison, or fluxbox, or compiz, etc.
exec ./visualdiagnostics
It's important to exec (become) the main program because once that first program exits, X will shut down.
Running fullscreen
I am not 100% certain on this. Some ideas:
Try the standard X -geometry parameters to set 0,0 as the upper-left corner and +x+y for your horizontal and vertical size. How do you know the size? Either you hard-coded it when you launched xinit or you could ask the X server. xwininfo -root will tell you and there is an xlib API call that would do that too—check the xwininfo source I guess.
Your app itself can request maximization and/or resizing to fill the screen. I'm not familiar but it is definitely in the X API.
Some of the more configurable window managers can be pre-configured to run you maximized already. This is probably what I personally would check first. Your wrapper script could create a $HOME/.fluxboxrc just by echoing some hard-coded configs > the file.
Summary
The others are right. X is not strictly necessary sine OpenGL can run against a framebuffer. However considering how ubiquitous X is and how much work has gone into automating it for distributions, I would probably invest my effort into the X route as it might be easier long-term even though it's a little convoluted.
(By the way, I sincerely hope when you say "terminal" you mean you are at the text console, not gnome-terminal that would be awful! :)
Well I am clearly not sure my answer might help you out.
Long ago when I was student, I manage to do so (launching an openGL app from a terminal only linux installation) by installing frame buffer. As long as I remember I needed to recompile my kernel (as framebuffer was/is a kernel module).
This was maybe 5 years ago on a debian distrib, and I don't know how does it work now for up-to-date debian distrib as Ubuntu. Maybe framebuffer is compiled statically in the binary kernel provided by default with Ubuntu. May be not. Maybe framebuffer is irrelevant now... Or I may be totally wrong and not remembering every details of my own adventure 5 years ago now ..
Have a look on Google ! ;-)
Hope it will help...
**
Update:
**
What is frame buffer ?
How to install it? Here or there
As yves pointed out, you can avoid running the X server if you use the framebuffer. Actually, the framebuffer modules are often yet available (for example, they are used to have the tux logo during the kernel start or a text terminal with fancy images in the background), this anyway depends on the distribution and the settings you are using.
The kernel side is quite primitive so I'd suggest to use some higher level library such as DirectFB. The framebuffer is usable without problems but don't expect the same maturity level than a full blown X server.
Are you trying to have the video be on the monitor connected directly to the computer?
Is X running on the server?
If X is running, you can do
export DISPLAY=:0.0
which tells X apps to connect to the X server at localhost, rather than where' you're coming from.
If you're actually logging in locally (from a direct terminal) ... yes, you need X installed and running.
If it's possible, I'm interested in being able to embed a PostgreSQL database, similar to sqllite. I've read that it's not possible. I'm no database expert though, so I want to hear from you.
Essentially I want PostgreSQL without all the configuration and installation. If it's possible, tell me how.
Run postgresql in a background process.
Start a separate thread in your application that would start a postgresql server in local mode either by binding it to localhost with some random free port or by using sockets (does windows support sockets?). That should be fairly easy, something like:
system("C:\Program Files\MyApplication\pgsql\postgres.exe -D C:\Documents and Settings\User\Local Settings\MyApplication\database -h 127.0.0.1 -p 12345");
and then just connect to 127.0.0.1:12345.
When your application quits, you can always send a SIGTERM to your thread and then wait a few seconds for postgresql to quit (ie join the thread).
PS: You can also use pg_ctl to control your "embedded" database, even without threads, just do a "pg_ctl start" (with appropriate options) when starting the application and "pg_ctl stop" when quitting it.
You cannot embed it, nor should you try.
For embedding you should use sqlite as you mentioned or firebird rdbms.
Unless you do a major rewrite of code, it is not possible to run Postgres "embedded". Either run it as a separate process or use something else. SQLite is an excellent choice. But there are others. MySQL has an embedded version. See it at http://mysql.com/oem/. Also several java choices, and Mac has Core Data you can write too. Hell, you can even use FoxPro. What OS you on and what services you need from the database?
You can't embed it as a in process type thing like sqlite etc, but you can easily embed it into your application setup using Inno setup at http://www.innosetup.org. Search their mailing list archive and you will find someone did most of the work for you and all you have to to is grab the zipped distro and you can easily have postgresql installed when the user installs your app. You can then use the pg_hba.conf file to restrict the server to local host only. Not a true embedded DB, but it would work.
PostgreSQL is intended to run as a stand-alone server; it's probably possible to embed it if you hack at it hard and long enough, but it would be much easier to just run it as intended in a separate process.
HSQLDB (http://hsqldb.org/) is another db which is easily embedded. Requires Java, but is an excellent and often-used choice for Java applications.
Anyone tried on Mac OS X:
http://pagesperso-orange.fr/bruno.gaufier/xhtml/prod_postgresql.xhtml
http://www.macosxguru.net/article.php?story=20041119135924825
(Of course sqlite would be my embedded db of choice as well)
Well, I know this is a very very very old post, but if anyone has nowadays this question, I would refer to:
You can use containers running Postgres. Here's a post that could be helpful, doing something along this line using R:
https://rsangole.netlify.app/post/2021/08/07/docker-based-rstudio-postgres/?utm_source=pocket_mylist
Take a look at duckdb https://duckdb.org/docs/installation/ It is relatively new and still needs to mature. But it works pretty much like an embedded database ("In-process, serverless"), with bindings for several languages (Python, R, Java, ...)