POSIX Compatibility List

File and Directories - <unistd.h>

Name	Synopsis	Description	Support?
getcwd	char *getcwd(char *buf, size_t size);	get current working directory
mkdir	int mkdir(const char *pathname, mode_t mode);	create a directory
rmdir	int rmdir(const char *pathname);	delete a directory
chdir	int chdir(const char *path);	change working directory
link	int link(const char *oldpath, const char *newpath);	make a new name for a file	X
unlink	int unlink(const char *pathname);	delete a name and possibly the file it refers to
rename	int rename(const char *oldpath, const char *newpath);	change the name or location of a file
stat	int stat(const char *file_name, struct stat *buf);	get file status
chmod	int chmod(const char *path, mode_t mode);	change permissions of a file	No
chown	int chown(const char *path, uid_t owner, gid_t group);	change ownership of a file	No
utime	int utime(const char *filename, struct utimbuf *buf);	change access and/or modification times of an inode	X
opendir	DIR *opendir(const char *name);	open a directory
readdir	struct dirent *readdir(DIR *dir);	read directory entry
closedir	int closedir(DIR *dir);	close a directory
rewinddir	void rewinddir(DIR *dir);	reset directory stream

Advanced File Operations - <unistd.h>

Name	Synopsis	Description	Support?
access	int access(const char *pathname, int mode);	check user's permissions for a file
open	int open(const char *pathname, int flags);	open and possibly create a file or device
creat	int creat(const char *pathname, mode_t mode);	open and possibly create a file or device
close	int close(int fd);	close a file descriptor
read	ssize_t read(int fd, void *buf, size_t count);	read from a file descriptor
write	ssize_t write(int fd, const void *buf, size_t count);	write to a file descriptor
fcntl	int fcntl(int fd, int cmd);	manipulate file descriptor	X
fstat	int fstat(int filedes, struct stat *buf);	get file status
lseek	off_t lseek(int fildes, off_t offset, int whence);	reposition read/write file offset
dup	int dup(int oldfd);	duplicate a file descriptor
dup2	int dup2(int oldfd, int newfd);	duplicate a file descriptor
pipe	int pipe(int filedes[2]);	create pipe	X
mkfifo	int mkfifo(const char *pathname, mode_t mode);	make a FIFO special file (a named pipe)	X
umask	mode_t umask(mode_t mask);	set file creation mask	Not Support
fdopen	FILE *fdopen(int fildes, const char *mode);	associate a stream with an existing file descriptor
fileno	int fileno(FILE *stream);	return file descriptor of stream

Processes - <unistd.h>

Name	Synopsis	Description	Support?
fork	pid_t fork(void);	create a child process
execl	int execl(const char *path, const char *arg, ...);	execute a file	X
execle	int execle(const char *path, const char *arg, ...)	execute a file	X
execlp	int execlp(const char *file, const char *arg, ...);	execute a file	X
execv	int execv(const char *path, char *const argv[]);	execute a file	X
execve	int execve(const char *path, char *const argv[], char *const envp[]))	execute program
execvp	int execvp(const char *file, char *const argv[]);	execute a file	X
wait	pid_t wait(int *status);	wait for process termination
waitpid	pid_t waitpid(pid_t pid, int *status, int options);	wait for process termination
_exit	void _exit(int status);	terminate the current process
kill	int kill(pid_t pid, int sig);	send signal to a process
sleep	unsigned int sleep(unsigned int seconds);	Sleep for the specified number of seconds
pause	int pause(void);	wait for signal
alarm	unsigned int alarm(unsigned int seconds);	set an alarm clock for delivery of a signal
setuid	int setuid(uid_t uid);	set user identity	Limited Support
setgid	int setgid(gid_t gid);	set group identity	Limited Support

Long Jumps - <setjmp.h>

Name	Synopsis	Description	Support?
setjmp	int setjmp(jmp_buf env);	save stack context for non-local goto
sigsetjmp	int sigsetjmp(sigjmp_buf env, int savesigs);	save stack context for non-local goto	X
longjmp	void longjmp(jmp_buf env, int val);	non-local jump to a saved stack context
siglongjmp	void siglongjmp(sigjmp_buf env, int val);	non-local jump to a saved stack context	X

Signal Handling - <signal.h>

Name	Synopsis	Description	Support?
sigaction	int sigaction(int sig, const struct sigaction *act, struct sigaction *oldact);	examine and change signal action
sigemptyset	int sigemptyset(sigset_t *set);	create an empty signal set	X
sigfillset	int sigfillset(sigset_t *set);	create a full set of signals	X
sigaddset	int sigaddset(sigset_t *set, int signum);	add a signal to a signal set	X
sigdelset	int sigdelset(sigset_t *set, int signum);	remove a signal from a signal set	X
sigismember	int sigismember(const sigset_t *set, int signum);	test a signal set for a selected member	X
sigprocmask	int sigprocmask(int how, const sigset_t *set, sigset_t *oset);	examine and change blocked signals
sigpending	int sigpending(sigset_t *set);	examine pending signals
sigsuspend	int sigsuspend(const sigset_t *mask);	wait for a signal

Obtaining Information at Runtime - <unistd.h><pwd.h><grp.h>

Name	Synopsis	Description	Support?
getpid	pid_t getpid(void);	get process identification
getppid	pid_t getppid(void);	get parent process identification
getlogin	char * getlogin(void);	get user name	X
getuid	uid_t getuid(void);	get user identity	Limited Support
geteuid	uid_t geteuid(void);	get effective user identity	Limited Support
cuserrid	char * cuserid(char *string);	get user name	X
getgid	gid_t getgid(void);	get group identity	Limited Support
getegid	gid_t getegid(void);	get effective group identity	Limited Support
getpwuid	struct passwd *getpwuid(uid_t uid);	get password file entry based on user id	X
getpwnam	struct passwd *getpwnam(const char * name);	get password file entry based on user name	X
getgrgid	struct group *getgrgid(gid_t gid);	get group file entry based on group id	X
getgrnam	struct group *getgrnam(const char *name);	get group file entry baes on group name	X
getgroups	int getgroups(int size, gid_t list[]);	get list of supplementary group IDs	X
ctermid	char *ctermid(char *s);	get controlling terminal name	X
uname	int uname(struct utsname *buf);	get name and information about current kernel
getenv	char *getenv(const char *name);	get an environment variable	X
sysconf	long sysconf(int name);	get configuration information at runtime	X
fpathconf	long fpathconf(int filedes, int name);	get configuration values for files	X
isatty	int isatty(int desc);	does this descriptor refer to a terminal	X
ttyname	char *ttyname(int desc);	return name of a terminal	X
times	clock_t times(struct tms *buf);	get process times	X
tzset	void tzset(void);	initialize time conversion information	X

Terminal I/O - <termios.h>

Name	Synopsis	Description	Support?
getpid	pid_t getpid(void);	get process identification	X
tcgetattr	int tcgetattr(int fd, struct termios *termios_p);	get terminal attributes	X
tcsetattr	int tcsetattr(int fd, int optional_actions, struct termios *termios_p);	set terminal attributes	X
tcdrain	int tcdrain(int fd);	wait for all output to be transmitted to the terminal	X
tcflow	int tcflow(int fd, int action);	suspend/restart terminal output	X
tcflush	int tcflush(int fd, int queue_selector);	discard terminal data	X
tcsendbreak	int tcsendbreak(int fd, int duration);	send a break to a terminal	X
cfgetispeed	speed_t cfgetispeed(struct termios *termios_p);	get input baud rate	X
cfgetospeed	speed_t cfgetospeed(struct termios *termios_p);	get output baud rate	X
cfsetispeed	int cfsetispeed(struct termios *termios_p, speed_t speed);	set input baud rate	X
cfsetospeed	speed_t cfsetospeed(const struct termios *termios_p);	set output baud rate	X
tcgetpgrp	pid_t tcgetpgrp(int fd);	get terminal foreground process group ID	X
tcsetpgrp	int tcsetpgrp(int fd, pid_t pgrpid);	set terminal foreground process group ID

Process Groups and Job Control - <unistd.h>

Name	Synopsis	Description	Support?
setsid	pid_t setsid(void);	creates a session and sets the process group ID	X
setpgid	int setpgid(pid_t pid, pid_t pgid);	set process group
getpgrp	pid_t getpgrp(void);	get process group