PID of a running process in C++

jegadezz · 05-25-2016, 08:54 AM

I am writing a code and I want to set CPU affinity of a process for which I need its PID . How can I read the pid of running processes in C++ code.

Any help is appreciable.

hazel · 05-25-2016, 10:47 AM

There's a C-library getpid() function that returns the PID of the current process. You can use getppid() to get the PID of the parent.

jegadezz · 05-25-2016, 12:09 PM

Hi Hazel , thanks for your reply . Actually I am looking for another independent process's id whose I know only the name . Its neither the child or parent process of my program.

HMW · 05-25-2016, 12:59 PM

How about something like this?

Code:

#include <stdio.h>
#include <stdlib.h>
#define LEN 10

int main()
{
	char line[LEN];
	FILE *cmd = popen("pidof -s cbatticon", "r");
	long pid = 0;

	fgets(line, LEN, cmd);
	pid = strtoul(line, NULL, 10);
	
	printf("%ld\n", pid);
	
	pclose(cmd);
	
	return 0;
}

My output:

Code:

$ ./myPidof 
365

My output from terminal:

Code:

pidof -s cbatticon
365
ps aux | grep cbatti | grep -v grep
HMW     365  0.0  1.1  63368 24276 tty1     Sl   18:51   0:02 cbatticon

Probably bug prone as hell, no expert at C (read: amateur!), mostly stolen from here:
http://stackoverflow.com/questions/8...x-in-c#8166467

Best regards,
HMW

sundialsvcs · 05-25-2016, 03:12 PM

Bear in mind, also, that "CPU affinity" is customarily set by rules, or heuristics, which do not presume prior knowledge of a particular PID. The exceptions are low-level system calls which presume that the PID is already known, e.g. by its parent.