- pid_t fork(void);
- pid_t wait(int *status);
- pid_t waitpid(pid_t pid, int *status, int options);
- int execvp(const char *file, char *const argv[]);
- int execlp(const char *file, const char *arg, ...);
- int open(const char *filename, int flags);
- int open(const char *filename, int flags, mode_t mode);
- int close(int fd);
- ssize_t read(int fd, void *buffer, size_t n);
- ssize_t write(int fd, const void *buffer, size_t n);
- int pipe(int pipefd[2]);
- int dup2(int old_fd, int new_fd);
- WIFEXITED(status)
- WEXITSTATUS(status)
- WTERMSIG(status)