Posted by hank, Sun Mar 30 21:16:00 UTC 2008
Today, I decided I wanted a network service that propagated variables and aliases to every login shell that subscribed to it. This is dangerous on a large scale, but perfectly acceptable on my small home network where everyone trusts everyone else.
First, I got Camping installed, bringing back fond memories of Ruby development. I then copied off the blog example, and created TreeHugger, a 427 line script that provides a web interface to edit the variables, and a plain text output for the shells to source.
This script, when run, allows some simple MVC actions to an sqlite3 database.
As you can see, I have some aliases here I want to send to all the subscribing hosts. Eventually, I want to add some detection functionality to the database (mostly reverse DNS lookups for host rule referencing). I just have to access /out to get my desired output:
# Treehugger Configuration
# Aliases
alias ai='sudo apt-get install'
alias aup='sudo apt-get update'
alias aug='sudo apt-get upgrade'
# Environment Variables
Now, to get this into bash. I looked into making the date command spit out pretty unique timestamps. Turns out you can do this with the nanoseconds format:
$ date +%s%N
1206926780157462141
I made it so wget saves the treehugger config to a tempfile using the somewhat random seed above as a filename suffix, and then I have my shell source it:
FILENAME=/tmp/treehugger-`date +%s%N`; 2>/dev/null wget -O $FILENAME http://rofl.who/treehugger/out && source $FILENAME && rm $FILENAME
And now I have nice aliases on my laptop served up from my desktop as fresh as the shell:
hank@davros:~$ alias
alias ai='sudo apt-get install'
alias aug='sudo apt-get upgrade'
alias aup='sudo apt-get update'
alias ls='ls --color=auto'
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