How to find if a process is running in C?

Question

I would like to find out if a process is running. I DO NOT want to use any system("") commands. Is there any C based function that lets you know if a process is running?

I would like to provide the process name and want to know if it's running.

Thanks,

Answer 1

Sure, use kill(2):

 #include <sys/types.h>
 #include <signal.h>

 int kill(pid_t pid, int sig);

If sig is 0, then no signal is sent, but error checking is still performed; this can be used to check for the existence of a process ID or process group ID.

So just call kill(pid, 0) on the process ID of the process that you want to check for and see if you get an error (ESRCH).

Answer 2

On Linux, another way to do this might include examining the contents of the /proc directory. Numbered directories are process IDs, while subdirectories containing the cmdline file show the name of the command.

For example, if /proc/1234/cmdline contains the value foo, then process foo has an ID of 1234. You could map names to PIDs this way, using standard file access functions in C. See proc(5) for more information.

Answer 3

You may find this interesting: http://programming-in-linux.blogspot.com/2008/03/get-process-id-by-name-in-c.html

The "conventional and best way" to do this is read the /proc folder. You can see this question for more, which references http://procps.sourceforge.net/, which may be of interest to you