Re: Default DNS lookup command?

[David Wright <deblis@lionunicorn.co.uk>]

On Sun 22 Oct 2023 at 11:07:05 (+0700), Max Nikulin wrote:
> On 21/10/2023 22:58, David Wright wrote:
> > On Sat 21 Oct 2023 at 17:35:21 (+0200), Reiner Buehl wrote:
> > > is there a DNS lookup command that is installed by default on any
> > > Debian Bullseye or Bookworm install?
> > 
> > nslookup is in busybox.
> 
> busybox is an optional package, so it may be absent. "getent hosts"
> from Greg's message is better in this sense. If systemd-resolved is
> configured on a particular instance then
> 
>     resolvectl query debian.org
> 
> may be an option.

AFAICT, if you don't have busybox installed, then I think it's likely
that you removed it yourself. The d-i initrd has busybox already installed,
and most people will see something like this in its log:

  # head -n2 /var/log/installer/syslog
  Jul 26 19:17:07 syslogd started: BusyBox v1.35.0
  Jul 26 19:17:07 kernel: klogd started: BusyBox v1.35.0 (Debian 1:1.35.0-4+b3)
  #

If the following file is still available (the one with the highest
generation number), you can see that busybox is typically the third
package to be installed by APT. (If the file has been rotated away,
just search for "busybox" in the file above.)

  # zcat /var/log/apt/history.log.2.gz | head

  Start-Date: 2023-07-26  19:30:49
  Commandline: apt-get -o APT::Status-Fd=4 -o APT::Keep-Fds::=5 -o APT::Keep-Fds::=6 -q -y --no-remove install locales
  Install: locales:i386 (2.36-9), libc-l10n:i386 (2.36-9, automatic)
  End-Date: 2023-07-26  19:30:56

  Start-Date: 2023-07-26  14:31:14
  Commandline: apt-get -o APT::Status-Fd=4 -o APT::Keep-Fds::=5 -o APT::Keep-Fds::=6 -q -y --no-remove install busybox
  Install: busybox:i386 (1:1.35.0-4+b3)
  End-Date: 2023-07-26  14:31:16
  # 

I suppose preseed experts might be able to prevent that from
happening, though to what purpose, IDK.

I can only assume that its Priority is set to Optional so that
it's easily removable if not required.

I don't see many reasons that systemd-resolved would get installed
unless you specifically asked for it, so I'd hardly call it
"installed by default".

Cheers,
David.