Re: [PATCH v2] send-email: try to get fqdn by running hostname --fqdn on Linux and macOS

From: Julian Swagemakers <julian@swagemakers.org>
Date: May 12, 2025, 07:46 UTC
Message-ID: <D9U0KAX6KVXK.WCY7YGX2Q0A5@swagemakers.org>
In-Reply-To: <PN3PR01MB9597BC2E1B526A11D21BAB24B895A@PN3PR01MB9597.INDPRD01.PROD.OUTLOOK.COM>

On Sat May 10, 2025 at 9:37 AM CEST, Aditya Garg wrote:

> `hostname` is a popular command available on both Linux and macOS. As
> per the man-page[1], `hostname --fqdn` command returns the fully
> qualified domain name (FQDN) of the system.

There are multiple implementations of the hostname command, and they don't all support `--fqdn`. For example this will not work on Alpine Linux as well as macOS.

macOS:

    $ hostname --fqdn
    hostname: illegal option -- -
    usage: hostname [-f] [-s | -d] [name-of-host]

Alpine:

    $ hostname --fqdn
    hostname: unrecognized option: fqdn
    BusyBox v1.37.0 (2025-01-17 18:12:01 UTC) multi-call binary.

    Usage: hostname [-sidf] [HOSTNAME | -F FILE]

    Show or set hostname or DNS domain name

        -s	Short
        -i	Addresses for the hostname
        -d	DNS domain name
        -f	Fully qualified domain name
        -F FILE	Use FILE's content as hostname

All seem to support `-f` though, maybe that would be the better option.

Regards Julian