The function trimdomain removes the current domain name from the passed fullhost name by writing a NUL character over the first period of the passed name. The current domain name is determined by calling gethostname(3) and removing everything up to the first period. The name is determined the first time this function is called and is cached for future use.
The trimdomain function will only trim the domain name if the passed fullname ends with the current domain name and if the length of the resulting host name does not exceed hostsize.
If the passed fullname is actually a DISPLAY specification of the form
.Sm off host. domain: nn[. nn ]
.Sm on and the domain name is the same as the local domain name, trimdomain will remove the embedded domain name, copying the screen and display numbers to the end of the base host name and resulting in
.Sm off host: nn [.nn].
The trimdomain function does not return a value.