On Saturday, March 16, 2024 2:06 PM, Ignacio Encinas Rubio wrote:

On 16/3/24 18:41, rsbecker@nexbridge.com wrote:

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On Saturday, March 16, 2024 1:03 PM, Junio C Hamano wrote:

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Jeff King [off-list ref] writes:

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Do we need to define "hostname" in more detail here? Specifically,
I'm wondering whether the result will be a FQDN or not (i.e., the
output of "hostname" vs "hostname -f"). Looking at the code I think
it will just be the short name returned. That's probably OK, but it
may be worth documenting.

That was my first reaction but there are places where "hostname"
already gives a name that is not "short" at all, without being
invoked with

"-f".

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For example, the (virtual) workstation I am typing this message on
sits in

a $WORK datacenter, where "hostname" gives the same

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string as "hostname -f", which looks like "git.c.xxxxxx.tld" ("git"
is the

only part I picked myself for it, "c" is shared by those employee

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workstations hosted at datacenters, "xxxxxx.tld" is redacted to
conceal the

real domain name to protect the culprits ;-).

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I think the most honest answer we can give in the documentation is
that we

use what gethostname() [*] gives.

I think this is probably a good idea and but value should not be
cached. My dev box has a multi-home, multi-cpu IP stack. It makes
things really weird sometimes. For example, hostname replies with:

ztc0.xxxxxxxx.local

and includes the current default IP stack, which is known to DNS,
while uname -n, which I prefer to use when deciding what system I am
on during tests, reports:

xxxxxxxx

I am not sure how meaningful hostname is; however, "hostname -f" is
not portable. However, includeif depending on whatever gethostname()
returns is reasonable, in my opinion, also. I think the series should
include a $(uname
-n) option in some form for completeness.

Correct me if I'm wrong, but gethostname() seems to be equivalent to $(uname -n)

Glibc definitely uses uname, according to its man page, but that is the exception, not the rule. Evidence from my experimentation on various platforms says that the two values may sometimes be the same but the host configuration may be different, particularly if two stacks are on the same machine with different IP addresses. uname does not go to DNS. gethostname() generally (Windows, S/390, NonStop, Linux where glibc is not used), uses DNS as its first attempt to resolve the name.