check_process_started.cpp

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <string>

std::string exec_cmd(std::string cmd) {
    if (cmd.empty()) {
        return "";
    }

    std::cout <<cmd <<std::endl;
    auto cmd_pipe = popen(cmd.c_str(), "r");
    if (nullptr == cmd_pipe) {
        return "";
    }

    char line_str[64] = "";
    if (nullptr == fgets(line_str, sizeof(line_str), cmd_pipe)) {
        pclose(cmd_pipe);
        return "";
    }
    pclose(cmd_pipe);
    return line_str;
}

pid_t get_process_id(std::string proc_name) {
    if (proc_name.empty()) {
        return -1;
    }

    int base = 10;
    std::string cmd = std::string("pidof -s ") + proc_name;
    auto line_str = exec_cmd(cmd);
    if (line_str.empty()) {
        return -1;
    }

    return strtoul(line_str.c_str(), nullptr, base);
}

bool process_started(std::string proc_name) {
    auto pid = get_process_id(proc_name);
    std::cout <<"pid:" <<pid <<std::endl;
    return !(pid < 0);
}

int main(int argc, char **argv) {
    if (argc != 2) {
        std::cout <<"usage: " <<argv[0] <<" programe" <<std::endl;
        return -1;
    }
    std::string prog = argv[1];
    if (process_started(prog)) {
        std::cout <<prog <<" started!" <<std::endl;
    } else {
        std::cout <<prog <<" not started!" <<std::endl;
    }
    return 0;
}