SETREUID(2) BSD System Calls Manual SETREUID(2)
setreuid -- set real and effective user ID's
Standard C Library (libc, -lc)
setreuid(uid_t ruid, uid_t euid);
The real and effective user IDs of the current process are set according
to the arguments. If ruid or euid is -1, the current uid is filled in by
the system. Unprivileged users may change the real user ID to the effec-
tive user ID and vice-versa; only the super-user may make other changes.
The setreuid() function has been used to swap the real and effective user
IDs in set-user-ID programs to temporarily relinquish the set-user-ID
value. This purpose is now better served by the use of the seteuid()
function (see setuid(2)).
When setting the real and effective user IDs to the same value, the stan-
dard setuid() function is preferred.
The setreuid() function returns the value 0 if successful; otherwise the
value -1 is returned and the global variable errno is set to indicate the
[EPERM] The current process is not the super-user and a change
other than changing the effective user-id to the real
user-id was specified.
getuid(2), issetugid(2), seteuid(2), setuid(2)
The setreuid() system call appeared in 4.2BSD.
BSD February 8, 2001 BSD