Host lookup that respects /etc/hosts

Question

Utilities like host and dig let you see the IP address corresponding to the host name.

There is also the getent utility that can be used to query /etc/hosts or other NSS databases.

I am looking for a convenient standard utility (which is available in Debian, say) which resolves a host name regardless of where it is defined.

It should be more or less equivalent to

ping "$HOST" | head -1 | perl -lne '/\((.*?)\)/ && print $1'

Yeah, I don't thing it could get more convenient than getent. — Bratchley, Apr 05 '13 at 20:19
@Patrick: hmm, I didn't realise `getent` also looks in DNS (I thought it only looks in `/etc/hosts`). Now that I've tried it, here's what's wrong with `getent`: for `google.com`, it returns a single address, and that address is IPv6. Which is not helpful, since I'm on an IPv4 network, and my command would actually print an IPv4 address. — Roman Cheplyaka, Apr 05 '13 at 20:48
@RomanCheplyaka - See eppesuig's answer that shows how to use getent to only look for IPv4 addresses: http://unix.stackexchange.com/a/71392/7453 — slm, Aug 29 '13 at 18:51

score 16 · Answer 1 · answered Apr 05 '13 at 21:37

16

If the problem is that you do not want to resolve these names using ipv6, then just ask getent to use ipv4 only. This will enumerate all ipv4 addresses:

giuseppe@blatta:~$ getent ahostsv4 www.google.com | cut -d' ' -f1 | sort -u
173.194.40.80
173.194.40.81
173.194.40.82
173.194.40.83
173.194.40.84

answered Apr 05 '13 at 21:37

eppesuig

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For those who do care to forget history (i.e. IPv4), use `ahostsv6`. – Luc Jul 06 '15 at 21:18
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For those who want to avoid considering the differences between IPv4 and IPv6, use `getent ahosts google.com`. – Mikko Rantalainen Oct 02 '17 at 10:02

score 5 · Answer 2 · answered Apr 05 '13 at 21:48

The thing is there are several APIs to resolve host names like gethostbyname, getaddrinfo and inet_pton and some of those can return more than one address and/or you can query the type of address you want.

If you want a portable way to get one IPv4 address, then maybe:

perl -MSocket -le 'print inet_ntoa inet_aton shift' www.google.com

score 4 · Accepted Answer · answered Apr 05 '13 at 21:09

4

The only command that I am aware that does what you want is resolveip:

http://linux.die.net/man/1/resolveip

However it only comes with mysql-server, which may not be ideal to install everywhere.

answered Apr 05 '13 at 21:09

Georgyo

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score 3 · Answer 4 · answered Nov 03 '13 at 20:57

3

gethostip -d name.domain from the syslinux package on Ubuntu (and probably Debian). -d outputs decimal format.

answered Nov 03 '13 at 20:57

dan3

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score 1 · Answer 5 · answered Apr 05 '13 at 22:24

1

(This answer only applies if you're root on the machine.)

I used to be annoyed by this too, and then I standardized on running dnsmasq on all my machines. Dnsmasq is a lightweight DNS cache. As a side benefit, it serves the content of /etc/hosts over DNS.

answered Apr 05 '13 at 22:24

Gilles 'SO- stop being evil'

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Daniel Alder · Answer 6 · 2015-10-11T14:44:48.740

I used my pure perl knowledge and made a little script with error handling:

/usr/local/bin/gethostip:

#!/usr/bin/perl

# inspired by: https://unix.stackexchange.com/questions/71379/host-lookup-that-respects-etc-hosts#71393

use strict;
use Socket;

my $name = $ARGV[0];
if ($name eq '') {
  print STDERR "Usage: gethostip <hostname>\n";
  exit 1;
}
my $ip = inet_aton($name);
die("Unable to resolve host name $name") if ($ip eq '');
my $ipstr = inet_ntoa($ip);
print "$ipstr\n";

Thx to Stéphane Chazelas for the initial idea

Host lookup that respects /etc/hosts

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