C++ execute linux cmd and retrieve the output

#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <vector>
#include <stdexcept>
#include <string>
#include <sstream>
#include <algorithm>

void execLinuxCmd(const char *cmd, vector<string> &vec)
{
    char buffer[128];
    FILE *pipe = popen(cmd, "r");
    if (!pipe)
    {
        throw std::runtime_error("popen() failed!");
    }
    stringstream ss;
    try
    {
        while (fgets(buffer, sizeof buffer, pipe) != NULL)
        {
            string lineResult(buffer);            
            const char * charFullName=lineResult.c_str();          
            char *fullName=(char*)malloc(128);
            realpath(charFullName,fullName);
            ss<<fullName<<endl;
            string strResult=ss.str();
            strResult=strResult.substr(0,strResult.length()-2);
            // strResult.erase(std::remove(strResult.begin(),strResult.end(),'
'),strResult.end());
            vec.push_back(strResult);
            ss=stringstream();
            free(fullName);
        }
    }
    catch (...)
    {
        cout<<"exception"<<endl;
        pclose(pipe);
        throw;
    }
    pclose(pipe);
}

void cmd18()
{
    string cmd="cd /home/fred/Work/NP/20211024/cpp;ls -r;";
    vector<string> vec;
    execLinuxCmd(cmd.c_str(),vec);
    vector<string>::iterator itr=vec.begin();
    while(itr!=vec.end())
    {
        cout<<*itr<<endl;
        itr++;
    }
}

 

/home/fred/Work/NP/20211024/cpp/h3.cpp
/home/fred/Work/NP/20211024/cpp/h2.cpp
/home/fred/Work/NP/20211024/cpp/h1.cpp
/home/fred/Work/NP/20211024/cpp/h1