O fork
syscall deve retornar -1 e definir errno
para EAGAIN . O que acontece depois disso dependerá do processo que chamou fork
.
De garfo :
The fork() function shall fail if:
[EAGAIN]
The system lacked the necessary resources to create another process, or the system-imposed limit on the total number of processes under execution system-wide or by a single user {CHILD_MAX} would be exceeded.