setreuid - Set real and effective user IDs
uid_t euid );
Interfaces documented on this reference page conform to
industry standards as follows:
setreuid(): XSH4.2, XSH5.0
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
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
Functions: getuid(2), setgid(2), setregid(2), setruid(3)
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