pipe()/fork()/execl() functions do not return output of external program

engintozal (2)
Hello, I am writing a program which calls an external program and gets its output. I implemented this functionality into a method. When I called the method for the first time it successfully obtains the output, however, when I called multiple times in the main() it does not obtain the output of the external program after the first call. Could anyone please help me. engin Below is the main structure of the method: ...::ally(){ allyString.clear();//to collect the output of external program pid_t pid; int commpipe[2]; int status; if(pipe(commpipe)==-1){ cout<<"Error in opening pipe"<<endl; exit(1); } pid=fork(); if(pid==-1){ cout<<"Error in forking"<<endl; exit(1); } if(pid>0){//parent process close(commpipe[1]); dup2(commpipe[0],0);//replace stdin with read side of pipe wait(&status);//wait for the child to finish while(!cin.eof()){ char c=cin.get(); allyString.push_back(c); } close(commpipe[0]); }else{//child process close(commpipe[0]); dup2(commpipe[1],1);//replace stdout with write side of pipe if(execl("/src/local/bin/ally", "ally","154.54.20.26", "154.54.20.26",(char *)0)==-1){//the external program cout<<"Error in executing the external ally program "<<endl; exit(1); } cout<<"Finished Child process"; close(commpipe[1]); } }