On my Linux box (Gentoo Linux 2.6.31 to be specific) I have noticed that the HOSTNAME environment variable is available in my shell, but not in scripts. For example,
$ echo $HOSTNAME returns
xxxxxxxx.com, but
$ ruby -e 'puts ENV["HOSTNAME"]' returns
nil On the other hand, the USER environment variable, for instance, is available both in the shell and in scripts.
I have noticed that USER appears in the list of environment variables that appears when I type
export i.e.,
declare -x USER="infogrind" but HOSTNAME doesn't. I suspect the issue has something to do with that.
My questions: 1) how can I make HOSTNAME available in scripts, and 2) for my better understanding, where is this variable initially set, and why is it not "exported"?
1 Answer
$HOSTNAME is a Bash variable that's set automatically (rather than in a startup file). Ruby probably runs sh for its shell and it doesn't include that variable. There's no reason you can't export it yourself.
bash$ echo $HOSTNAME foobar bash$ sh -c 'echo $HOSTNAME' bash$ export HOSTNAME bash$ sh -c 'echo $HOSTNAME' foobar You could add the export command to one of your startup files, such as ~/.bashrc.
In Ruby (irb shown):
>> require 'socket' => true >> Socket.gethostname => "bazinga" 
