+extern int dup2(int oldfd, int newfd);
+
+extern int chown(const char *path, uid_t owner, gid_t group);
+
+#define S_ISUID 04000
+#define S_ISGID 02000
+#define S_ISVTX 01000
+#define S_IRWXU 00700
+#define S_IRUSR 00400
+#define S_IWUSR 00300
+#define S_IXUSR 00100
+#define S_IRWXG 00070
+#define S_IRGRP 00040
+#define S_IWGRP 00020
+#define S_IXGRP 00010
+#define S_IRWXO 0007
+#define S_IROTH 00004
+#define S_IWOTH 00002
+#define S_IXOTH 00001
+extern int chmod(const char *path, mode_t mode);
+
+extern pid_t setsid(void);
+
+extern uid_t getuid(void);
+//extern int setuid(uid_t uid);
+extern uid_t geteuid(void);
+extern pid_t getpid(void);
+extern int seteuid(uid_t euid);
+extern int setegid(gid_t egid);
+//extern int setgid(gid_t gid);
+
+typedef uint32_t useconds_t;
+
+extern unsigned int sleep(unsigned int seconds);
+extern int usleep(useconds_t usec);
+
+// - crypt.c
+extern char *crypt(const char *key, const char *salt);
+
+// - pty.c
+extern char *ttyname(int fd);
+extern int ttyname_r(int fd, char *buf, size_t buflen);
+
+// signal.h / sys/types.h
+extern int kill(pid_t pid, int sig);
+
+extern int chdir(const char *dir);
+extern int rmdir(const char *pathname);
+
+// Deprecated POSIX.1-2001
+#define PASS_MAX 63
+extern char *getpass(const char *prompt);
+