---
name: "trimdomain"
section: "3"
platform: "macos"
package: "libutil"
version: "73"
release: "macOS 26.5"
platforms: ["freebsd", "macos"]
url: "https://new.carta.tech/trimdomain"
---

# trimdomain(3)

trim the current domain name from a host name

## NAME

**trimdomain** – trim the current domain name from a host name

## LIBRARY

System Utilities Library (libutil, -lutil)

## SYNOPSIS

**#include \<sys/types.h\>**

**#include \<libutil.h\>**

*void*\

**trimdomain**(*char \*fullhost*, *int hostsize*);

## DESCRIPTION

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)](/gethostname/3.md) 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 *host*.*domain*:*nn*\[. *nn*\] 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 *host*:*nn*\[.*nn*\].

## RETURN VALUES

The **trimdomain**() function does not return a value.

## SEE ALSO

[gethostname(3)](/gethostname/3.md)