Get the child of a process by its name in Linux

process_child.cpp

#include <algorithm>
#include <vector>
#include <iostream>
#include <fstream>

#include <proc/readproc.h>


void ProcIdFromParentProcId(int parentProcId, std::vector<int>& procId) {
  PROCTAB *proc = openproc(PROC_FILLSTAT);
  while (proc_t *proc_info = readproc(proc, nullptr)) {
    if (proc_info->ppid == parentProcId) {
      procId.push_back(proc_info->tgid);// i++;
    }
    freeproc(proc_info);
  }
}

pid_t get_pid_by_name(std::string name){
  char buf[512];
  std::string command = "pidof -s " + name;
  
  FILE *cmd_pipe = popen(command.c_str(), "r");

  fgets(buf, 512, cmd_pipe);
  pid_t pid = strtoul(buf, NULL, 10);

  pclose( cmd_pipe );
  
  return pid;
}

std::string get_name_by_pid(pid_t pid){
  char file_path[100];
  sprintf(file_path, "/proc/%d/task/%d/comm", pid, pid);
  std::ifstream file(file_path);
  
  std::string proc_name;
  std::getline(file, proc_name);
  
  return proc_name;
  
}


int main(){
  std::vector<int> procs;

  std::string process_name;
  std::cout<<"Enter the process name: ";
  std::cin>>process_name;

  //Get PID by name
  int pid_process = get_pid_by_name(process_name);
  std::cout<<"The PID of this process is: "<<pid_process<<"\n";
  
  //Get child process by PID
  ProcIdFromParentProcId(pid_process, procs);
  
  std::cout<<"The child process are: ";
  for(int i = 0; i < procs.size(); i++){
    pid_t pid = procs[i];
    std::string proc_name = get_name_by_pid(pid);
  
    std::cout<<pid<<"("<<proc_name<<")\n";
  }
  std::cout<<std::endl;
  
  return 0;
}