进程篇：

//功能：创建子线程获取进程编号

pid_t fork(void);

pid_t getpid(void);

pid_t getppid(void);

//功能：完全替换当前线程的内容

extern char **environ;

int execl(const char *path, const char *arg, .../* (char *) NULL */);
int execlp(const char *file, const char *arg, .../* (char *) NULL */);
int execle(const char *path, const char *arg, .../*, (char *) NULL, char * const envp[] */);
int execv(const char *path, char *const argv[]);
int execvp(const char *file, char *const argv[]);
int execvpe(const char *file, char *const argv[],char *const envp[]);

//功能：等待子线程结束

pid_t wait(int *status);

pid_t waitpid(pid_t pid, int *status, int options);

int waitid(idtype_t idtype, id_t id, siginfo_t *infop, int options); /* This is the glibc and POSIX interface; see NOTES for information on the raw system call. */

信号篇：

//功能：信号集函数

int sigemptyset(sigset_t *set);

int sigfillset(sigset_t *set);

int sigaddset(sigset_t *set, int signum);

int sigdelset(sigset_t *set, int signum);

int sigismember(const sigset_t *set, int signum);

//功能：原子化信号等待操作(替换pause())

int sigsuspend(const sigset_t *mask);(mask 为 sigprocmask备份的oldset)

//功能：信号屏蔽字

int sigprocmask(int how, const sigset_t *set, sigset_t *oldset);

//功能：信号处理函数(替换signal())

int sigaction(int signum, const struct sigaction *act,struct sigaction *oldact);

//功能：定时时间函数(替换alarm())

int getitimer(int which, struct itimerval *curr_value);
int setitimer(int which, const struct itimerval *new_value, struct itimerval *old_value);

//功能：向指定进程或进程组发送指定信号

int kill(pid_t pid, int sig);