program that reacts to inotify and prints the events - c++

Question

I am working in Ubuntu. I want to monitor a folder and print every event that pops up in the subfolders (print files).
I have the following code but it doesn't work. When executed, there is no println of the events.
In the second code I only see the events from the folder. The events from each subfolder do not pop up.
#include <string>
#include <iostream>
#include <stdio.h>
using namespace std;
std::string exec(char* cmd) {
FILE* pipe = popen(cmd, "r");
if (!pipe) return "ERROR";
char buffer[256];
std::string result = "";
while(!feof(pipe)) {
if(fgets(buffer, 256, pipe) != NULL)
result += buffer;
}
pclose(pipe);
cout<<"result is: "<<result<<endl;
return result;
}
int main()
{
//while(1)
//{
string s=exec((char*)"inotifywait -rme create /home/folder/");
cout << s << endl;
//}
return 0;
}
This code only prints the events from the folder I'm monitoring. It doesn't print the events from each subfolder. I don't know how to improve it for my needs.
#include <sys/inotify.h>
#include <sys/ioctl.h>
#include <iostream>
void processNewFiles(int fd, int wd);
int main(int argc, char** argv)
{
const char* dirPath = "/home/folder/" ;//argv[1];
int fd = inotify_init();
int wd = inotify_add_watch(fd, dirPath, IN_CREATE);
if (wd)
{
processNewFiles(fd, wd);
inotify_rm_watch(fd, wd);
}
}
void processNewFiles(int fd, int wd)
{
bool done = false;
do
{
int qLen = 0;
ioctl(fd, FIONREAD, &qLen);
char* buf = new char[qLen];
int num = read(fd, buf, qLen);
if (num == qLen)
{
inotify_event* iev = reinterpret_cast<inotify_event*>(buf);
if (iev->wd == wd && iev->mask & IN_CREATE)
{
std::cout << "New file created: " << iev->name << std::endl;
}
}
delete [] buf;
} while (!done);
}

Answer 1

Your second solution does not work because inotify_add_watch is not working recursivly. You would have to add watches for subdirectories manually. As this might be annoying, it is also possible to use the utility inotifywait as you do in your first example.
Your first example is not working because you're reading from the pipe forever. If you kill the inotifywait process (e.g. if you're the only person on the machine and this is the only inotifywait process just using "killall inotifywait") you will get your output because you'll break out of the loop reading from the pipe. If you output something inside the loop, it will work, too.