extern int unlink(const char *pathname);
+#define F_OK 00
+#define R_OK 04
+#define W_OK 02
+#define X_OK 01
extern int access(const char *pathname, int mode);
extern pid_t setsid(void);
extern char *crypt(const char *key, const char *salt);
// - pty.c
+extern int isatty(int fd);
extern char *ttyname(int fd);
extern int ttyname_r(int fd, char *buf, size_t buflen);