Pipes executes command only once - c

Question

I'm new on StackOverflow and learning about pipes in C. I'm trying to make a shell interpeter that allows introducing 2 commands linked by pipe like
/bin/ls -l | /bin/grep a
I have a main which have a function that reads a command, then main calls a function that searchs for a "|" and if it finds it, the function makes 2 commands from it, then that function calls another one which executes the commands. My problem is that it just works once. If I introduce a command with pipes it executes it perfectly, but if I do it again it doesn't work, like the directory had change. It doesn't matter that the first command has pipes or not, the second command (if it has pipes) wont execute correctly. I think it's because of the pipes, the code of the function that execute the pipes:
void execute_pipes(char *** command1, char *** command2){
pid_t son;
int tube2[2];
pipe(tube2);
son=fork();
if(son==0){//son1
dup2(tube2[1], STDOUT_FILENO);
close(tube2[0]);
if(execv((*command1)[0],*command1)==-1){
printf("Error");
exit(0);
}
}else{//father
son=fork();
if(son==0){//son2
dup2(tube2[0], STDIN_FILENO);
close(tube2[1]);
if(execv((*command2)[0],*command2)==-1){
printf("Error");
exit(0);
}
}else{//father
close(tube2[0]);
close(tube2[1]);
waitpid(son, NULL, 0);
}
}
}
I'm sure that the parameters are ok, ending with a NULL parameter (if not I guess it wouldnt execute one time). In each new read, a new pipe is created. I guess that the last pipe won't affect this new one but I don't know...
An example of this:
/home/user/Desktop$ /bin/ls -l | /bin/grep -
-rw-rw-r-- 1 user user 435 dec 18 02:33 filename
drwxrwsr-x 9 user user 4096 dec 20 19:23 filename
-rwxrwxr-x 1 user user 14464 dec 20 20:29 filename
-rw-rw-r-- 1 user user 3580430 dec 5 03:24 filename
-rw-rw-r-- 1 user user 6833 dec 20 20:05 filename
-rw-rw-r-- 1 user user 6772 dec 20 18:48 filename
-rw-rw-r-- 1 user user 1226 dec 19 21:48 filename
-rwxrwxr-x 1 user user 8704 dec 18 16:23 filename
-rw-rw-r-- 1 user user 33673847 oct 17 20:50 filename
/home/user/Desktop$ /bin/ls -l | /bin/grep -
-rwxr-xr-x 1 root root 126584 feb 18 2016 /bin/ls
/home/user/Desktop$
NOTE: I've changed my username for 'user' and the names of the files for 'filename'.
Thanks whoever who reads this.
Summarising: my code only executes a command correctly one time, the second time it doesn't work properly and I don't know why, but I guess the problem are the pipes.

Answer 1

I can't comment yet, so I'm posting it as an answer. Welcome to SO. It will be easier for people to help you if you provide a working example, which I think you can. Here is a guide How to create a Minimal, Complete, and Verifiable example
Unfortunately I can't get your code to work. Maybe looking at an example implementation of a lightweight shell will help you. Here is the source code for xv6 shell. Search for PIPE keyword.
xv6 is a re-implementation of Dennis Ritchie's and Ken Thompson's Unix
Version 6 (v6).

Answer 2

Oke, I solved the problem, it was a problem of the initialization of the parameters. It was in a function I didn't write because I supposed it worked.
The only doubt I have now is why was even able to execute...
Thanks everyone for answering me .