The Fn user_from_uid function returns the user name associated with the argument Fa uid . The user name is cached so that multiple calls with the same Fa uid do not require additional calls to getpwuid(3). If there is no user associated with the Fa uid , a pointer is returned to an ASCII representation of the Fa uid , unless the argument Fa nouser is non-zero, in which case a NULL pointer is returned.
The Fn group_from_gid function returns the group name associated with the argument Fa gid . The group name is cached so that multiple calls with the same Fa gid do not require additional calls to getgrgid(3). If there is no group associated with the Fa gid , a pointer is returned to an ASCII representation of the Fa gid , unless the argument Fa nogroup is non-zero, in which case a NULL pointer is returned.