SETREUIDSection: Linux Programmer's Manual (2)
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NAMEsetreuid, setregid - set real and/or effective user or group ID
DESCRIPTIONsetreuid() sets real and effective user IDs of the current process.
Supplying a value of -1 for either the real or effective user ID forces the system to leave that ID unchanged.
Unprivileged processes may only set the effective user ID to the real user ID, the effective user ID or the saved set-user-ID.
POSIX: It is unspecified whether unprivileged processes may set the real user ID to the real user ID, the effective user ID or the saved set-user-ID.
Linux: Unprivileged users may only set the real user ID to the real user ID or the effective user ID.
Linux: If the real user ID is set or the effective user ID is set to a value not equal to the previous real user ID, the saved set-user-ID will be set to the new effective user ID.
RETURN VALUEOn success, zero is returned. On error, -1 is returned, and errno is set appropriately.
- The current process is not privileged (Linux: does not have the CAP_SETUID capability in the case of setreuid(), or the CAP_SETGID capability in the case of setregid()) and a change other than (i) swapping the effective user (group) ID with the real user (group) ID, or (ii) setting one to the value of the other or (iii) setting the effective user (group) ID to the value of the saved set-user-ID (saved set-group-ID) was specified.
CONFORMING TOPOSIX.1-2001, 4.3BSD (the setreuid() and setregid() function calls first appeared in 4.2BSD).
NOTESSetting the effective user (group) ID to the saved set-user-ID (saved set-group-ID) is possible since Linux 1.1.37 (1.1.38).
SEE ALSOgetgid(2), getuid(2), seteuid(2), setgid(2), setresuid(2), setuid(2), capabilities(7)