/*process management*/ pid_t	fork(void); pid_t	waitpid(pid_t pid,size_t *status,size_t options);size_t	execve(const char *name,char *const *argv,char *const* envp);void	exit(size_t status);pid_t	getpid();pid_t	getppid();/*signals*/size_t	sigaction(size_t sig,void *(*fpt)(void *));<br />size_t	sigreturn();size_t	sigprocmask();size_t	sigpending();size_t	sigsuspend();size_t	pause();size_t	alarm(time_t seconds);size_t	kill(pid_t pid,size_t sig);/*file system management*/size_t	create(const char *name,mode_t mod);size_t	open(const char *name,size_t flag,mode_t mode);size_t	read(size_t fd,void *buf,size_t nbytes);size_t	write(size_t fd,const void *buf,size_t nbytes);size_t	close(size_t fd);off_t	lseek(size_t fd,off_t pos,size_t how);size_t	stat(const char *name,struct stat *buf);size_t	fstat(size_t fd,struct stat *buf);size_t	access(const char *nam,int a_mode);size_t	rename(const char *old_name,const char *new_name);size_t	dump(size_t fd);size_t	ioctl(size_t fd,size_t cmd,size_t option);size_t	fcntl(size_t fd,size_t cmd,size_t option);size_t	pipe(size_t *fd);size_t	mknod(const char *name,mode_t mode,dev_t dev);size_t	mkdir(const char *name,mode_t mode);size_t	rmdir(const char *name);size_t	link(const char *old_name,const char *new_name);size_t	unlink(const char *name);size_t	sync();size_t	chdir(const char *name);size_t	chroot(const char *name);size_t	fchdir(size_t fd);size_t	faccess(size_t fd,size_t amode);size_t	getcwd(const char *buf,size_t size);size_t	mount(const char *dev_name,const char *dir_name,const char *type,unsigned long flags,const void *data);size_t	umount(const char *dir_name,unsigned long flags);size_t	getdents(size_t fd,struct dirents *dents,size_t counts);/*Protection*/<br />size_t	chmod(const char *name,mode_t mode);size_t	chown(const char *name,uid_t uid,gid_t gid);uid_t	getuid();gid_t	getgid();size_t	setuid(uid_t uid);size_t	setgid(gid_t gid);mode_t	umask(mode_t mode);size_t	fchmod(size_t fd,mode_t mode);size_t	fchown(size_t fd,uid_t uid,gid_t gid);/*time management*/time_t	time(time_t *ret); /*Get the elapsed time since Jan 1,1970*/size_t	stime(time_t when); /*set time since Jan 1,1970*/size_t	utime(const char *name,time_t last); /*set last access for file*/size_t	times(struct tm *tbuf);size_t	sleep(time_t seconds);	size_t	nanosleep(struct timespec *rqtp,struct timespec *rmtp);