$HOSTNAME shell script not working

Ricio · 07-22-2008, 03:56 PM

hello all,

well im learning bash scripting, and Im trying to write a few programs and all reading the beginners guide to bash from tldp.org.

Thing is that a script im doing does not show echo $HOSTNAME variable, which is weird cuz when I do echo $HOSTNAME on terminal it shows it but when I do it on the script does not display anything...
can anyone help me out?

matthewg42 · 07-22-2008, 04:22 PM

Sometimes HOST or HOSTNAME may be set in the system wide profile, but you should not rely on it. Instead there is a program called hostname, which you can call and assign the output to a variable in your script like this:

Code:

HOST=$(hostname)

Mr. C. · 07-22-2008, 05:12 PM

HOSTNAME is set when you run bash, but not sh. Example:

Code:

$ cat ./showhostname 
#!/bin/sh

echo hostname: $HOSTNAME
$ ./showhostname        
hostname: 

$ cat ./showhostname 
#!/bin/bash

echo hostname: $HOSTNAME
$ ./showhostname        
hostname: myhost.example.com

smoked kipper · 07-23-2008, 12:37 PM

/bin/sh might not set it, but it shouldn't unset it if it's already set. Make sure it's exported and it will propagate into sub-shells. Put an

export HOSTNAME

in /etc/profile (after setting it as described by matthewg42, if the profile doesn't set it (it may be setting it but not exporting it)) and it will be inherited by all shells (unless the're specifically started with a clean environment, e.g. via env -i).

Ricio · 07-23-2008, 02:18 PM

Great, thank you all... proved all 3 responses and they all do what I wanted to... Thank you!