I am using a program (PiAUISuite, http://stevenhickson.blogspot.com.es/) that I cannot find how to kill the process. Looking at the code (https://github.com/StevenHickson/PiAUISuite) I can see that it checks if the pid_file is empty or not, so it definitively employs it but I cannot find where is the file. Once the program is running, there's nothing in /var/run (at least that I can see).
Then the question is, how to properly kill a process in linux (raspberry pi, raspbian) when you don't know if the program offers such funcionality. And if you want to kill it through the PID, how to find where the PID_FILE is, provided that it seems that the program uses one?
I use 'sudo killall voicecommand'
Related
I am trying to find a way to identify and kill specific processes in a Mac Application. Is there a built-in class that has functions that can return the list of running processes? There is one way of running terminal commands using Process() and execute the /usr/bin/killall command to kill processes but I need to do it programmatically as running terminal commands using an application is not a good practice. For example, deleting a file can also be done by running a terminal command using Process() while the better way to do it is using FileManager.default.remomveItem().
If you're looking for an application (rather than a process), then see NSWorkspace.shared.runningApplications. You can call terminate() or forceTerminate() on those elements.
If you want a list of all BSD processes (what you would get from a call to ps for example), that's done with sysctl (the code in the Q&A is in C; you'd have to wrap it to Swift, or rewrite it). I don't believe there's any Cocoa wrapper for that. To kill a process, once you have its PID, use signal, which is what the kill Unix command uses. Typically you want to send SIGTERM, which is a normal shutdown. To force-kill a process, send SIGKILL.
I am learning to write character device drivers from the Kernel Module Programming Guide, and used mknod to create a node in /dev to talk to my driver.
However, I cannot find any obvious way to remove it, after checking the manpage and observing that rmnod is a non-existent command.
What is the correct way to reverse the effect of mknod, and safely remove the node created in /dev?
The correct command is just rm :)
A device node created by mknod is just a file that contains a device major and minor number. When you access that file the first time, Linux looks for a driver that advertises that major/minor and loads it. Your driver then handles all I/O with that file.
When you delete a device node, the usual Un*x file behavior aplies: Linux will wait until there are no more references to the file and then it will be deleted from disk.
Your driver doesn't really notice anything of this. Linux does not automatically unload modules. Your driver wil simply no longer receive requests to do anything. But it will be ready in case anybody recreates the device node.
You are probably looking for a function rather than a command. unlink() is the answer. unlink() will remove the file/special file if no process has the file open. If any processes have the file open, then the file will remain until the last file descriptor referring to it is closed. Read more here: http://man7.org/linux/man-pages/man2/unlink.2.html
I'm looking at hosting a number of small, static websites and have been looking at a few alternatives including G-WAN. At the moment I'm just trying to get a feel for how well each server suits my needs before picking one.
G-WAN seems to do exactly what I want, though I'm running into problems with updating the configuration (by adding new folders) after the server's started. I can't find anything in the documentation or online about this, so I don't know if I'm doing anything dumb, running an unsupported configuration, or whether it's a feature that doesn't exist in G-WAN.
Here's my setup:
G-WAN 3.3.28 64-bit on Ubuntu 12.04.1 LTS.
I have what I think is the required minimal folder structure:
0.0.0.0_80
#0.0.0.0
www
$site.com
www
$othersite.com
www
I startup gwan via (I'm still messing around, so hopefully ):
sudo .\gwan -d
Everything works brilliantly. I add $thirdsite.com/, $thirdsite.com/www/, and $thirdsite.com/www/index.html; then when I try to visit thirdsite.com it gives me the root host (ie it doesn't seem to pick up the changes).
To reload the modified configuration, I have to either do:
sudo .\gwan -k; sudo .\gwan -d
or kill the non-angel process (kill -s 15) to restart the child process.
Can G-WAN reload the host definitions another way? If so, is it something that works out of the box or is there a command that can cycle the server without dropping requests made to other hosts (/is it safe to kill -s 15 on the non-angel process + if so, is there a reliable way to identify the process)? Thanks in advance!
G-WAN loads the host definitions at startup and does not check them as time goes to reload them dynamically.
To force a reload, you have to stop the child process (when in daemon mode) and v3.9+ keeps the old child alive the time to process any pending request while the new child accepts new connections.
Since stopping the child can also be done from the maintenance script or from a handler or from a servlet by just running exit(0) there is not need for a dedicated command.
Note that when you use kill you can pick the pid file from the gwan directory:
the parent process starts with a capital letter: Gwan_xxxx.pid
the child process starts with a lowercase letter: gwan_xxxx.pid
That will make your life easier.
I have a shell script which archives log files based on the whether the process is running or not. If the log file is not used by the process then I archive it. Until now, I'm using lsof to get the log file being used but in future, I have decided to use perl to do this function.
Is there a perl module similar to what lsof in linux can perform ?
There is a perl module, which wraps around lsof. See Unix::Lsof.
As I see it, the big problem with not using lsof is that one would need to work in a way that is independent of the operating system. Using lsof allows the perl programmer to work with a consistent application allowing for operating system independence.
To have a perl module developer to write lsof would, in effect, be writing lsof as a library and then link that into perl - which is much more work than just using the existing binary.
One could also use the fuser command, which shows the process IDs with the file handle. There is also a module which seeks to implement the same functionality. Note from the perldoc:
The way that this works is highly unlikely to work on any other OS
other than Linux and even then it may not work on other than 2.2.*
kernels.
One might try walking /proc/*/fd and looking at the file descriptors in there to see if any are pointing to the file in question. If it is known what the process ID of a running process that would be opening the log file, it would be just as easy to look at that process. Note, that this is how the fuser module works.
That said, it should be asked "why do you want to move away from lsof"?
I'm working with an embedded computer that has a Debian on it. I already manage to run a command just before it has booted and play the "bell" to tell that is ready to work, and for example try to connect to a service.
The problem is that I need to play the bell (or run any command/program) when the system is halted so is safe to un-plug the power. Is there any runscript that run just after halt?
If you have a look in /etc/init.d, you'll see a script called halt. I'm pretty certain that when /sbin/halt is called in a runlevel other than 0 or 6, it calls /sbin/shutdown, which runs this script (unless called with an -n flag). So maybe you could add your own hook into that script? Obviously, it would be before the final halt was called, but nothing runs after that, so maybe that's ok.
Another option would be to use the fact that all running processes get sent a SIGTERM followed (a second or so later) by a SIGKILL. So you could write a simple daemon that just sat there until given a SIGTERM, at which point it went "ping" and died.