Listing Processes

oriel_gizmo · 08-20-2004, 01:59 AM

Is there any way of listing all processes on linux in C, as i am trying to emulate the EnumWindows function in windows.

Kumar · 08-20-2004, 02:20 AM

You can get them from the /proc. check the man page for more info.

oriel_gizmo · 08-20-2004, 02:48 AM

how do you found out the active ones

oriel_gizmo · 08-20-2004, 02:56 AM

are the ones on the /proc directory all active processes. If a process finished is the pid cleared from the /proc diectory

gizmo_thunder · 08-20-2004, 03:01 AM

yes all the processes in the proc file system are either running , stopped .
if by active you mean running.. processes.. then refer to the man page
to know how to know if the process is running or suspended.

Kumar · 08-20-2004, 03:29 AM

Check the file /proc/<pid>/status. It has everything you need.

Hko · 08-20-2004, 05:40 AM

Does this help:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>
#include <fnmatch.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>


void processdir(const struct dirent *dir)
{
     puts(dir->d_name);
}


/* This function shows how to get information from the /proc/<pid>
 * directory.  In this case it reads and filters on the owner 
 * of the file (this is also the owner of the process)
 *
 * If you want to list ALL PID's, just remove the part
 * that check for the user.
 */
int filter(const struct dirent *dir)
{
     uid_t user;
     struct stat dirinfo;
     int len = strlen(dir->d_name) + 7; 
     char path[len];

     strcpy(path, "/proc/");
     strcat(path, dir->d_name);

     user = getuid();
     if (stat(path, &dirinfo) < 0) {
          perror("processdir() ==> stat()");
          exit(EXIT_FAILURE); 
     }
     return !fnmatch("[1-9]*", dir->d_name, 0) && user == dirinfo.st_uid;
}


int main() {

     /* Based on example in "man scandir" */

     struct dirent **namelist;
     int n;

     n = scandir("/proc", &namelist, filter, 0);
     if (n < 0)
          perror("Not enough memory.");
     else {
          while(n--) {
               processdir(namelist[n]);
               free(namelist[n]);
          }
          free(namelist);
     }
     return 0;
}