Pfthb

When I run this code, i have "Segmentation fault (core dumped)".
Apparently it comes from the wait() section but I can't figure it out.

int main(int argc, char** argv)

 
pid_t pid, pid2;
int etat;
char** entree_util;
entree_util[0]="none";
char * accueil = "Veuillez entrer votre commanden";
while (entree_util[0]!="^D")

 write(1,accueil, strlen(accueil)*sizeof(char) );
 entree_util=lis_ligne();
 pid=fork();
 if(pid==-1)
 
 perror("Erreur à l'appel de forkn");
 exit(-1);
 
 else if(pid==0)
 
 execv(entree_util[0],entree_util+1);
 
 else
 
 pid2 = wait(&etat);
 

return 0; 

The first instance of undefined behavior in your code is

char** entree_util;
entree_util[0]="none";

entree_util is an uninitialized pointer.

You should probably change your loop structure:

char** entree_util;

while (1)

 write(1, accueil, strlen(accueil)); // note: sizeof (char) is 1 by definition
 entree_util = lis_ligne();
 if (we_are_finished(entree_util)) 
 break;
 
 ...

Note that entree_util[0] != "^D" doesn't make sense as a condition; you're not comparing strings here, you're comparing pointers. The correct condition depends on what lis_ligne returns, which you haven't shown.

Alternatively you can move the logic for prompting the user and reading a line into a separate helper function:

char **lis_ligne_avec_invite_de_commande(const char *accueil) 
 write(1, accueil, strlen(accueil));
 return lis_ligne();

and then use it like this:

char** entree_util;
while (!we_are_finished(entree_util = lis_ligne_avec_invite_de_commande("Veuillez entrer votre commanden"))

 ...