Re: $HOST on OS X

["Benjamin R. Haskell" <zsh@benizi.com>]

On Sat, 5 Jun 2010, Benjamin R. Haskell wrote:

> On Sat, 5 Jun 2010, William G. Scott wrote:
> 
> > Dear citizens:
> > 
> > I just noticed odd behavior for how $HOST is getting set on OS X v. 
> > 10.6.3.
> > 
> > One one home machine connected to a wireless router and ADSL modem:
> > 
> > % print $HOST
> > internalcheck.apple.com
> > 
> > On another -- This one worries me more:
> > 
> > % print $HOST
> > e3191.c.akamaiedge.net
> > 
> > The manual says $HOST is automatically set by the shell, but I wonder 
> > how this is happening?  I don't have anything weird in /etc/hosts for 
> > example...
> 
> $HOST is set by the following lines in Src/params.c:
> 
> 682    hostnam = (char *)zalloc(256);
> 683    gethostname(hostnam, 256);
> 684    setsparam("HOST", ztrdup(hostnam));
> 
> If gethostname is defined in unistd.h, it's a standard library call that 
> fills its char* first parameter with your hostname.  Otherwise, there's 
> a compatibility replacement in Src/compat.c that basically gets the node 
> name via uname.  Omitting error-checking, it's:
> 
> int gethostname(char*name, size_t namelen) {
>     struct utsname uts;
>     uname(&uts);
>     strcpy(name,uts.nodename);
> }
> 
> So, either way, it follows a pretty standard path to getting a hostname.
> 
> I'm not sure whether OS X would have gethostname, but what does `uname 
> -n` return?  Or `hostname`?

I also neglected to mention that $HOST can be inherited from the 
environment.

e.g.:
$ HOST=whatever zsh -c 'echo $HOST'
whatever
$

So, maybe there was some script you/someone ran that set 
HOST=e3191.c.akamaiedge.net, for convenience.  (For uploading things to 
Akamai's CDN, maybe?  Seems a bit of a stretch.)

-- 
Best,
Ben