SETRUID(3) Library Functions Manual SETRUID(3)

setruid, setrgid
set user and group ID

Standard C Library (libc, -lc)

#include <sys/types.h>

int
setruid(uid_t ruid);

int
setrgid(gid_t rgid);

The setruid() function (setrgid()) sets the real user ID (group ID) of the current process.

Upon success, these functions return 0; otherwise -1 is returned.

If the user is not the super user, or the uid specified is not the real or effective ID, these functions return -1.

The use of these calls is not portable. Their use is discouraged; they will be removed in the future.

getgid(2), getuid(2), setegid(2), seteuid(2), setgid(2), setuid(2)

The setruid() and setrgid() syscalls appeared in 4.2BSD and were dropped in 4.4BSD.
June 2, 1993 NetBSD 9.2