#include <unistd.h>

int setgid(gid_t gid);


Declared, not implemented


IEEE Std 1003.1-2017


If the process has appropriate privileges, setgid() shall set the real group ID, effective group ID, and the saved set-group-ID of the calling process to gid.

If the process does not have appropriate privileges, but gid is equal to the real group ID or the saved set-group-ID, setgid() shall set the effective group ID to gid; the real group ID and saved set-group-ID shall remain unchanged.

The setgid() function shall not affect the supplementary group list in any way.

Any supplementary group IDs of the calling process shall remain unchanged.

Return value

Upon successful completion, 0 is returned. Otherwise, -1 shall be returned and errno set to indicate the error.


The setgid() function shall fail if:

  • EINVAL - The value of the gid argument is invalid and is not supported by the implementation.

  • EPERM - The process does not have appropriate privileges and gid does not match the real group ID or the saved set-group-ID.



Known bugs


See Also

  1. Standard library functions
  2. Table of Contents