I have an linux app that uses cups for printing, but I've noticed that if I print and then quit my app right away my printout never appears. So I assume that my app has to wait for it to actually come out of the printer before quitting, so does anyone know how to tell when it's finished printing??
I'm using libcups to print a postscript file that my app generates. So I use the command to print the file and it then returns back to my app. So my app thinks that the document is off to the printer queue when I guess it has not made it there yet. So rather than have all my users have to look on the screen for the printer icon in the system tray I would rather have a solution in code, so if they try and quit before it has really been sent off I can alert them to the fact. Also the file I generate is a temporary file so it would be nice to know when it is finished with so I can delete it.
As soon as your CUPS web interface (localhost:631) or some other thing to look at what CUPS sees shows you that CUPS received the job, you can quit the application.
How about using a print spool service like lpr & lpq?
You certainly do not need to wait till the paper is out of the printer. However, you need to wait until your temporary file is fully received by cupsd in its spooling aerea (usually /var/spool/cups/).
If you printed on the commandline (using one of the CUPS lp or lpr commands) you'd know the job is underway if the shell prompt returns (the command will even report the CUPS job ID for the job sent), and if the exit code ($?) is 0.
You do not indicate which part of libcups and which function call you are using to achieve what you want. If I'd have to do this, I'd use the IPP function cupsSendRequest and then cupsGetResponse to know the result.
Your app likely hadn't finished printing yet when you quit it. If you're using evince to print a PDF or other document, this is a known bug--there is no visual confirmation that the printing operation is underway. If the print job has been submitted, a printer icon will appear in your system tray until the actual printing has finished. You can click on the printer icon in the system tray and see what jobs are currently running and pending.
Related
I have a LiveCode app standalone that needs to know if there is a job waiting in the MacOS print queue before printing. If app user 1 prints the 2 page report and just one page prints (out of paper) then user 2 comes along and prints the report, the first page out is user 1's report and this is causing mixups. I would like to check the MacOS print queue and prevent printing if there is a job already waiting.
It's not something I've ever needed to do, but I suspect that this capability is not included in LiveCode natively. Instead your best bet will probably be to use LiveCode's shell() function to run a unix terminal command. For instance, lpstat is a command line utility that allows you to query various things about printers connected to your Mac. The following command, run in the MacOS terminal, shows which printers are available and their current status.
lpstat -p
In LiveCode you use the shell() function to call this command line utility, like so:
put shell("lpstat -p") into tPrinterStatus
To find out more about lpstat, open the Terminal and look up the man page:
man lpstat
Lots of options for that utility will appear. There should be one that gives you the information you need.
I want to make a some kind of alert to let me know when the charger has disconnected (the cable doesn't fit into the socket well).
I have this to detect the status of the charger:
cat /sys/class/power_supply/ADP1/online
it returns 1 when charging and 0 when on battery.
and this to request a pop-up window:
zenity --info --text="Charger unplugged!"
I figured some kind of if statement would do the job, having to run it infinitely every second or so.
Then I remembered my days of Arduino where you could program an interrupt, that could trigger the script to run, rather than having to run it all the time.
Not sure what the best way to achieve this is. Does anybody know?
Many thanks.
You could create a service, or you can do it in a more simple and primitive way: create a script that will create a fork, redirect it's own stdout and stderr to /dev/null and execute an infinite loop that will be constantly checking your /sys/class/power_supply/ADP1/online file. When the value is 0 it will redirect the stdout and stderr to the original, in order to show the prompt. To make this an autonomous script, you would have to execute it with crontab #reboot.
I think that in the CLI it should work, but I don't know if it would work in a Graphical Desktop Interface
There's quite a bit of information out there on this topic, but for some reason I just can't get it to work. This is on a raspberry pi running the 'DietPi' flavor over the raspian distro, and is perhaps what separates my question from the others.
So I have a GUI application that I wish to launch at boot, after the LXDE session has begun. So I have utilized the following file here:
/etc/xdg/lxsession/LXDE/autostart
and added the line:
#/myapplication
This works, however, it launches multiple instances of this program, and the first one always crashes. This creates problems because there's some competition for resources (IO, files, etc). So what I did was create script file, /myapplication-autostart.sh instead like so:
if pgrep "myapplication" > /dev/null
then
echo "my application is already running"
else
/myapplication
fi
and then changed /etc/xdg/lxsession/LXDE/autostart to #/myapplication-autostart.sh. Now what I find is the program launches once, but the instance crashes. It crashes when it attempts to create a window (opencv imshow). This is strange because the program will also run headless if an X-session is not available, but for some reason it crashes and I do not know where to check why.
Also, to test it wasn't an issue with the script file, I commented everything out except the /myapplication and I have found the script file runs in a continuous loop and every time I close the application it opens back up. I'm not sure why this is either.
I've tried adding a sleep delay in the script and it does not help. For whatever reason, it seems the LXDE autostart script is ran at least 3 times when booting the pi and the circumstances around the first cause the program to crash. Does anybody understand this sequence and behavior of calling this autostart script?
It is also possible to use the XDG standard Autostart - which is independent of the used desktop environment - by placing desktop files at
$XDG_CONFIG_HOME/autostart (by default ~/.config/autostart)
or for system-wide autostarts at $XDG_CONFIG_DIRS/autostart (by default /etc/xdg/autostart).
Such a .desktop-file could look like:
[Desktop Entry]
Type=Application
Version=1.0
Name=JDownloader
Exec=/usr/local/bin/my-application.sh
Categories=Utilities
The specification of desktop-files can be found at freedesktop.org.
Here was the final solution...
/etc/xdg/lxsession/LXDE/autostart added the line:
/myapplication-autostart.sh
and /myapplication-autostart.sh was changed to:
#!/bin/bash
if pgrep "myapplication" > /dev/null
then
echo "my application is already running"
else
if [[ "$DISPLAY" = ":0" ]]
then
/myapplication
fi
fi
I had to write the display variable to file in combination with the errors to file to discover the issue. At login 2 X sessions were created, display ":1" and display ":0", in that sequence. Display ":1" crashed because, although not headless, it was not initialized to a particular resolution and there was some resizing code in my program. Display ":0" was the actual display on the HDMI out and the one I wanted. Really, the conditional check to see if the application isn't necessary but I left it in there to be safe. I could have also left the # on the LXDE autostart file but it got annoying in the cases I wanted to close the application because it'd keep re-opening. Possibly I'll put it back later.
Thanks for the help!
First, some comments about opening several instances of the program: when you use "#" at the beginning of the line on the startup file (ex.: #/myapplication), this requests your system to try to launch the program, but if the program fails to open correctly, then the system will try to open it multiple times until it opens correctly -- if you remove "#" from the line beginning, then the system will only try to open the program once.
Now, to find out why the program is failing, I advise you to add
2> /file/log
to the end of every command on your script. Doing so would append any error message to a log (/file/log), and analyzing those error messages would be key to find out why the program is misbehaving.
One important note: if your program needs root privileges to run, then it will fail when called via /etc/xdg/lxsession/LXDE/autostart, as this method calls programs without elevated permissions.
This is an old thread but I was having problems getting autostart to start all the tasks listed. After many days I concluded there were one or more "invisible" characters that autostart didn't like. So I deleted the lines for the tasks that didn't start and retyped them. That solved the problem!
I think I corrupted the lines because I was editing some of the lines on my Windows computer. It was likely inserting CR with LF or some other stuff. I WILL NEVER EDIT TEXT FOR LINUX USING WINDOWS!
Maybe someone else will hit this problem and this may help them. I don't know where else to put this information.
EDIT, the question might have not been totally clear, short version:
How to popup a dialog asking for user input if the script is running in the background and not in an active console?
/EDIT
When I run a bash script from udev or cron, it usually runs quietly somewhere in the background. Example could be plugging in an external harddrive runs rsync for data backup. So not every time I plug in the harddrive do I want to launch this action.
What is the most minimal way to fire up some user input dialog and ask yes or no? I could write some interface with PyQt but I want as little dependencies as possible, ideally cross window manager and maybe even without window manager.
Thanks!
EDIT 2: The lightweight (and hence as ugly as expected) version is xmessage, this would probably be the answer to the question, unless you have a better one:
xmessage "Do you want to run the backup script?" -buttons yes,no
http://linux.byexamples.com/archives/87/using-gui-dialog-box/
EDIT: So there's KDialog for kde, is there something really lightweight for X?
http://www.linux-magazine.com/Issues/2009/99/Zenity-and-KDialog
kdialog --title "Do you want to run the backup script?"
--yesno "Do you want to run the backup script?"
I'm currently leaning towards zenity, only trouble is it pulls in a whole array of gtk dependencies on kde, but is cross platform and works on windows. In essence, this is exaclty what I was looking for:
if zenity --question --text="Please press a button."; then
zenity --info --text="You pressed Yes\!"
else
zenity --error --text="You pressed No\!"
fi
But was hoping it would be a lot lighter on the resources / dependencies. Any alternative suggestions?
A simple approach would be for the automated script to simply email you, or perhaps alert with wall with instructions (containing the location of the real script).
Another approach would be for the automated script to touch a file in /var/lib and proceed if the file is still present after 5 minutes. This gives the user the option to stop the process (by removing the file), but maintains some automation.
This is not something you should have cron or udev handling in the first place. Write a userland daemon that listens for the appropriate D-Bus messages and performs the appropriate actions.
This should be post in linux or superuser or serverfault.
But, the number one google search on linux read user input links back here to StackOverflow:
https://www.google.com/search?q=linux+read+user+input&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=fflb
so I guess it's not too off base.
Again, the third or so google result for linux invoke command usb device plugin links to ServerFault:
https://serverfault.com/questions/399698/execute-a-command-when-a-device-is-connected-via-usb
I'll leave combining those two as an exercise.
In VC++, how to access text continuously from console window and print it in a CListBox? Infact I have a MFC program which calls other FORTRAN exe. The output of the FORTRAN exe comes in the console window. I need to print it in a CListBox continuously. I can print it in a file and can print it at one shot. But that is not my purpose. I need continuous feed. Can any one help me out of this?
_popen may work for you, see http://msdn.microsoft.com/en-us/library/96ayss4b%28VS.80%29.aspx
This Microsoft article should get you most of the way there:
How to spawn console processes with redirected standard handles