Analisis PID directorio proc/PID/cmdline

#include <stdio.h>
#include <dirent.h> // DIR
#include <string>
#include <iostream>
using namespace std;

//proc/pid/cmdline
int main(int argc, char* argv[])
{
    DIR* proc;// /proc

    FILE *fd ;
    //char cmdline[128];
    string cmdline;
  char *arg = 0; //Lecture cmdline dans le pid  proc/pid/cmdline
    size_t argsize = 0;

    struct dirent *ent;

    proc = opendir("/proc");
    while ((ent = readdir(proc)))
      {
        if ((*ent->d_name>'0') && (*ent->d_name<='9')) //numerique ,est un pid
          {
      cout <<"PID NUM="<< ent->d_name<<endl;

      //sprintf(cmdline, "/proc/%s/cmdline", ent->d_name);//cmdline
      cmdline+="/proc/"+string (ent->d_name)+"/cmdline";

      cout <<"cmdline = "<<cmdline<<endl;

      fd = fopen(cmdline.c_str(), "r");//ouvrur cmdline dans le pid

      if (fd == NULL) {cout <<"cmdline Error"<<endl;}
      else {
        while(getdelim(&arg, &argsize, '\0', fd) != -1){
          cout<<'\t'<<" cmdline ="<<arg<<endl;
        }
      }
      if (fd!=NULL) {fclose (fd);};//fermer file descriptor cmdline
          }
          cmdline.clear();
      }
    closedir(proc);
}