How to get the hostname from /etc/hostname & DNS domain name?

Question

How do I get the host name from /etc/hosts? by writing hostname? And what about the dns domain name, how do I get that? How do I get these names through the commandline?

Solution 1

When you type

hostname

it will show you the value that is stored in

/etc/hostname

See hostname --help for a lot of options. From the help ...

-s, --short            short host name
-a, --alias            alias names
-i, --ip-address       addresses for the host name
-I, --all-ip-addresses all addresses for the host
-f, --fqdn, --long     long host name (FQDN)
-A, --all-fqdns        all long host names (FQDNs)
-d, --domain           DNS domain name
-y, --yp, --nis        NIS/YP domain name
-b, --boot             set default hostname if none available
-F, --file             read host name or NIS domain name from given file

This command can get or set the host name or the NIS domain name. You can also get the DNS domain or the FQDN (fully qualified domain name). Unless you are using bind or NIS for host lookups you can change the FQDN (Fully Qualified Domain Name) and the DNS domain name (which is part of the FQDN) in the /etc/hosts file.

---

So

hostname -f

for the long host name (FQDN).

Solution 2

Presuming you want your local (LAN) IPv4 address....

To avoid your server returning a long string that combines your IPv4 and IPv6 addresses, use this programmatically in a bash script:

LOCALIP=$(hostname -I | awk '{print $1}')

Or type this on the CLI:

hostname -I | awk '{print $1}'

Comments

[Melebius]

Related: unix.stackexchange.com/questions/186859/…

[dada dudu]

I get: "hostname: Name or service not known"

[Rinzwind]

Do you have something in /etc/hostname? That one we here typically edit for apache. example topic: askubuntu.com/a/218499/15811

[dada dudu]

Have tried to cat /etc/hosts I get a localhost which I shouldn't as I run it on a VM

[Melebius]

@dadadudu localhost is just a nickname for “myself” on a network. All computers (including VM’s) can connect to themselves using localhost address.

[Rinzwind]

@dadadudu the VM I have here has its own name (it is called "test1").

[dada dudu]

but is localhost the then? And what about the dns domain name? I get the same error

[dada dudu]

When I write hostname, it gives me server03

[David Foerster]

This only works well if the host has only a single IPv4 address. IPv6 hosts typically have multiple IPv6 addresses (one permanent and one or more temporary).

[MrPotatoHead]

Right. That's why the 1st line of my suggestion is, "Presuming you want your local (LAN) IPv4 address...." But to your point, 'hostname' is not always the best tool for IP info. Depends on the goal. The OP was not detailed in his/her question about what they wanted (presumably the FQDN, but that is speculation on my part).