uid_t euid );
Interfaces documented on this reference page conform to industry standards as follows:
Refer to the standards(5) reference page for more information about industry standards and associated tags.
Specifies the new real user ID. Specifies the new effective user ID.
The setreuid() function sets the real and effective user IDs of the current process to the values specified by the ruid and euid parameters. If ruid or euid is -1, the corresponding effective or real user ID of the current process is not changed.
Users may change the effective user ID to the real user ID; only processes with superuser privilege may make other changes. This task is normally done by the system's authentication program (for example, login), but is not done for system daemons.
Upon successful completion, a value of 0 (zero) is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.
The setreuid() function sets errno to the specified values for the following conditions: The value of the ruid or euid parameter is invalid or out of range. The current process is not the superuser and a change other than changing the effective user ID to the real user ID was specified.
Functions: getuid(2), setgid(2), setregid(2), setruid(3)
Standards: standards(5) delim off