I don't want to use system() in my C program, because system(3) blocks and this is not what I want. What is the optimal way to do it?
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- Does this answer your question? Non-blocking version of system()Maxpm– Maxpm2021-01-10 04:40:57 +00:00Commented Jan 10, 2021 at 4:40
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5 Answers
I think that a quick and dirty action is to call sytem(command &). the & will spawn the new process.
2 Comments
DevSolar
Absolutely +1.
system() is platform-dependent anyway. Instead of making a mess of your source with fork() or stuff like that, use the shell that system() gives you access to.
Martin Meeser
great solution much better than fork if you aks me
Use fork() to create a new process and then use system() (or any exec function) in it. The original process will then be able to continue executing.
Comments
The answer depends on what your real goal is. You don't say what platform you're on, and I know very little about Windows, so this only covers your options on linux/unix.
You just want to spawn another program, and don't need to interact with it. In this case, call
fork(), and then in the child process runexecve()(or related function).You want to interact with another program. In this case, use
popen().You want part of your program to run as a subprocess. In this case, use
fork(), and call whatever functions you need to run in the child.You need to interact with part of your program running as a subprocess. Call
pipe()so you have a file descriptor to communicate through, then callfork()and use the file descriptor pair to communicate. Alternatively, you could communicate through a socket, message queue, shared memory, etc.
2 Comments
Matt Joiner
Nice rundown of the options at hand, and how to choose between them.
jilles
fork() then system() will leave a useless process hanging around for the shell to finish. It is better to call execve() or similar in the child process instead of system(). If you want to use the shell's features, then exec /bin/sh.You might want to use popen. It creates new processes and allows you to redirect the process output to your own process.
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If in windows, use the ShellExecute() function from the Windows API.
If in Unix, go for fork() then system() as mentioned.
