I want to add a linked list in kernel (linux) that is recognised by init process , I can add processes to it by adding system call , and they should be deleted from the list automatically when their parent wait for them .
I think about adding linked list as field in task_struct .
Can you help me in deleting the process from this linked list after it’s parent wait for it . I think that I should do this in release task function ...
Related
I have wrote an initialization script that sets user environment variables which are keys that have been hashed and encrypted...Once the keys have been created the key encryption exe is no longer required. I want to launch the main application and remove the init file containing the hashing and key encryption functions.
I am not having any trouble with any of the above...Everything works as should when independent of each other. The problem is that in order for the main application to have access to the newly created environment variables I need the init script to completely exit...
Everything I have tried, Popen with flags, os.system() and others have still left me in a situation where the parent process ends and the main application launches, however, the environment variables have not updated...I close and relaunch main.py and...boom the program sees the updated variables and all is fine.
All I want is the init script to run, spawn a new process that is not linked at all with init.py and then exit so it can be removed. I thought this would be simple but after many hours of head scratching and trying numerous things, I am still no closer.
If I have to I will simply bundle it as two separate .exe files but I wanted it to be a one click install type thing.
I am running windows 10 and this can be platform specific.
Links looked at:
How to stop/terminate a python script from running?
Using a Python subprocess call to invoke a Python script
Starting a separate process
https://docs.python.org/2/library/subprocess.html
Python: Howto launch a full process not a child process and retrieve the PID
And more...
Current closest result
p = Popen(["python","UserInterface.py"], stdin=PIPE, stdout=PIPE, stderr=PIPE,
creationflags=DETACHED_PROCESS | CREATE_NEW_PROCESS_GROUP)
Create an environment block, set the environment variable using SetEnvironmentVariable, and use CreateProcess to specify this environment block for the created process.
MSDN DOC:
To specify a different environment for a process, create a new
environment block and pass the pointer to it as a parameter to the
CreateProcess function.
...
To programmatically add or modify system environment variables, add
them to the
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session
Manager\Environment registry key, then broadcast a WM_SETTINGCHANGE
message with lParam set to the string "Environment". This allows
applications, such as the shell, to pick up your updates.
Julia contains a number of methods for making temporary files and directories.
I'm making fairly heavy use of them (and /dev/shm), to inferface with libraries that really want to work with actual files (JLD/HDF5, and OpenStack Swift).
I had been assuming they would be deleted when their finalisers on the pointer to there name were called.
But then after exiting julia it seemed like they were all still there.
Will linux delete them?
If the app didn't clean after itself, the OS will delete the files eventually. It depends on system settings when temp files are deleted. For example, it can happen on boot or nightly (via cron job) or some another way.
See this answer, for example: How is the /tmp directory cleaned up?
What you are likely looking for,
given your surprise that they were not removed, based on going out of scope, as the do block versions of mktemp.
In the very documentation you linked.
mktemp(f::Function[, parent=tempdir()])
Apply the function f to the result of mktemp(parent) and remove the temporary file upon completion.
mktempdir(f::Function[, parent=tempdir()])
Apply the function f to the result of mktempdir(parent) and remove the temporary directory upon completion.
Which you can use like:
mktempdir("/dev/shm") do tdir
fname = joinpath(tdir, name)
#Do some things with your new temp filename `fname` in your tempdir `tdir`
end
#the directory referenced by `tdir`, and `fname`, have now been deleted.
I have a program that can be ran several times. The program uses a working directory where it saves/manipulates its runtime files and puts results. I want to make sure that if several copies of the program run simultaneously, they won't use the same folder. To do this I add a hidden file in the work directory when it's created, that means that the directory is being used, and delete it when the program exits. When a program wants to use a certain directory as its working directory, it'll check if that file exists, and if not it will use the directory, otherwise, it'll use a directory of the same name with its process id attached. The implementation is: (in Tcl)
upon starting:
if [file exists [db_work_area]/.folder_used] {
reg set work_area_override [db_work_area]_[pid]
}
...
exec touch ${db_wa}/.folder_used
when exiting:
if [file exists [db_work_area]/.folder_used] {
file delete [db_work_area]/.folder_used
}
This works when the copies of the program are opened one at a time, however I am afraid that if several copies of the program will be opened at the same time, there will be a problem with their synchronization. Meaning that two programs will check if the file exists, together, see that it doesn't both chose that directory, and only after that, they will add the file. How can I implement a semaphore that will be able to synchronize between the several different copies of the same program running?
You should not do a [file exists] and later the touch, it works better to use open to do it in a single step with the EXCL permission.
Try to use something like this to create the file and fail if it already exists in an atomic way.
if {[catch {open ${db_wa}/.folder_used {WRONLY EXCL CREAT}} fd]} {
# error happend, file exists
# pick a different area
} else {
# just close it again, like a touch to create the file
close $fd
}
I have a requirement, I need to create multiple processes for the same exe.I know I can use createprocess(""myapp.exe,,,,,,,,,) function to create a single process and which will create a process with the name "myapp.exe" and run that exe also.
Now all i need is to create process for the same exe .lets say processes like "myapp1.exe" ,"myapp2.exe"..... and so on.
Please help me how to do this in VC++.
Thanks a lot
Processes don't have names. CreateProcess("myapp.exe", ...) doesn't create a process with the name "myapp.exe"". It creates an anonymous process, running myapp.exe.
hi all:
recently i'm working on make checkpoint on linux process and encountered a problem,it looks like that when i munmap memory map of the executable to current process,the symlink /proc/self/exe is dead.what i want is to make this symlink pointing to a other executable(the one for my resumed processs),is that possible?i tried delete it and recreate, permission denied. english is not my native language, i hope i've made my point,thanx
prctl(PR_SET_MM_EXE_FILE, ...)
Supersede the /proc/pid/exe symbolic link with a new one pointing to a new executable file identified by the file descriptor provided in arg3 argument. The file descriptor should be obtained with a regular open(2) call.
No. /proc is completely managed by the kernel and does not allow changes like that.
But you may be able to start a new process (with fork() perhaps) and map your memory snapshot into that.