CODEWITHSUNDEEP
bash
MoreScratch
MoreScratch

Reputation: 3083

Bash get string value

I have to get the hostname for a network device out of its config file. The file looks like:

...
hostname=T14Z18
ipaddress=192.168.0.1
...

How does one do that? I am ssh'ing into the machine.

Upvotes: 3

Views: 90

Answers (3)

Gilles Quénot
Gilles Quénot

Reputation: 185025

With - if -P regex switch is implemented :

grep -oP 'hostname=\K.*' configfile
                   __
                    ^
                    |

restart the match trick

Support of \K in regex

Upvotes: 2

Arkadiusz Drabczyk
Arkadiusz Drabczyk

Reputation: 12383

Use grep and cut like that:

$ grep '^hostname=' configfile  | cut -d= -f2
T14Z18

You can also combine the above with ssh command in Bash:

$ ssh "$(grep '^hostname=' configfile | cut -d= -f2)"

Everything between $( and ) will be replaced by the output of the command inside the parenthesis so it would be the same as if you typed ssh T14Z18 manually. This feature is called command substitution in Bash.

Also notice that OpenSSH that you probably use has its own config stored in ~/.ssh/config that you can use to create aliases. For example, the following entry creates an alias called rpi:

Host rpi
User pi
Hostname 192.168.1.161

You can now just do ssh rpi and user and hostname will be found automatically by OpenSSH client. You can of course use a hostname such as T14Z18 is in your example instead of IP address if you have DNS server in your network.

Upvotes: 3

RomanPerekhrest
RomanPerekhrest

Reputation: 92854

With simple awk command:

awk -F'=' '$1 == "hostname"{ print $2; exit }' configfile

Upvotes: 3

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