set real and effective group
The real and effective group IDs of the current process are set according to the arguments. The saved group ID will be set to the new value of the real group ID if a real group ID is specified and either the new real group ID value is different from the current value or the new value of the effective group ID differs from the current saved group ID.
Unprivileged users may change either group ID to the current value of the real, effective, or saved group ID. Only the superuser may make other changes.
Supplying a value of -1 for either the real or effective group ID forces the system to substitute the current ID in place of the -1 parameter.
function was intended to allow swapping the real and effective group IDs in
set-group-ID programs to temporarily relinquish the set-group-ID value. This
purpose is now better served by the use of the
When setting the real and effective group IDs to the same value, the setgid(2) function is preferred.
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
- The current process is not the superuser and a change other than changing the effective group ID to the real group ID was specified.
getgid(2), setegid(2), setgid(2), setresgid(2), setreuid(2)
setregid() function conforms to the
IEEE Std 1003.1-2008 (“POSIX.1”)
specification, except that the conditions for changing the saved group ID
differ and that, if it is changed, the saved group ID is set to the real
group ID instead of the effective group ID.
setregid() system call first appeared
in 4.1cBSD, predating POSIX. A semantically
different version appeared in 4.4BSD. The current
version, with the original semantics restored, appeared in