SETRESUID(2) BSD System Calls Manual SETRESUID(2)NAME
getresgid, getresuid, setresgid, setresuid — get or set real, effective
and saved user or group ID
Standard C Library (libc, -lc)
getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid);
getresuid(uid_t *ruid, uid_t *euid, uid_t *suid);
setresgid(gid_t rgid, gid_t egid, gid_t sgid);
setresuid(uid_t ruid, uid_t euid, uid_t suid);
The setresuid() system call sets the real, effective and saved user IDs
of the current process. The analogous setresgid() sets the real, effec‐
tive and saved group IDs.
Privileged processes may set these IDs to arbitrary values. Unprivileged
processes are restricted in that each of the new IDs must match one of
the current IDs.
Passing -1 as an argument causes the corresponding value to remain
The getresgid() and getresuid() calls retrieve the real, effective, and
saved group and user IDs of the current process, respectively.
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable errno is set to indicate the
[EPERM] The calling process was not privileged and tried to
change one or more IDs to a value which was not the
current real ID, the current effective ID nor the cur‐
rent saved ID.
[EFAULT] An address passed to getresgid() or getresuid() was
SEE ALSOgetegid(2), geteuid(2), getgid(2), getuid(2), issetugid(2), setgid(2),
setregid(2), setreuid(2), setuid(2)STANDARDS
These system calls are not available on many platforms. They exist in
FreeBSD to support Linux binaries linked against GNU libc2.
These functions first appeared in HP-UX.
BSD April 13, 2001 BSD