setresgid(2) - Linux man page
Name
setresuid, setresgid - set real, effective and saved user or group IDSynopsis
#define _GNU_SOURCE#include <unistd.h>
int setresuid(uid_t ruid, uid_t euid, uid_t suid);
int setresgid(gid_t rgid, gid_t egid, gid_t sgid);
Description
Unprivileged user processes may change the real UID, effective UID, and saved set-user-ID, each to one of: the current real UID, the current effective UID or the current saved set-user-ID.
Privileged processes (on Linux, those having the CAP_SETUID capability) may set the real UID, effective UID, and saved set-user-ID to arbitrary values.
If one of the parameters equals -1, the corresponding value is not changed.
Regardless of what changes are made to the real UID, effective UID, and saved set-user-ID, the file system UID is always set to the same value as the (possibly new) effective UID.
Completely analogously, setresgid() sets the real GID, effective GID, and saved set-group-ID of the current process (and always modifies the file system GID to be the same as the effective GID), with the same restrictions for non-privileged processes.
Return Value
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.Errors
- EAGAIN
- uid does not match the current UID and this call would bring that user ID over its NPROC rlimit.
- EPERM
- The calling process is not privileged (did not have the CAP_SETUID capability) and tried to change the IDs to values that are not permitted.
