Function and Alias use in bash

Sun, 1 Oct 2006 00:49:38 GMT

For a while now ive been using aliases to connect to machines. I alias a $hostname to xterm -T $hostname -e ssh $hostname &. This means each connection gets a new fresh xterm. Of course doing an alias command for each host woudl be tedious so i have some magic in bash startup stuff.

bob@betty:~ >cat .bashrc 
[ -f ~/.bash_aliases ] && . ~/.bash_aliases
PS1="\u@\h:\w >"
PATH=$PATH:/usr/sbin:/usr/local/sbin:/sbin
bob@betty:~ >cat .bash_aliases 
for MACHINE in `cat ~/.machines`
do
alias $MACHINE="xterm -T $MACHINE -e ssh $MACHINE &"
done

Where .machines is a list of machines one per line

Recently I have been connecting to machines which arnt in this list with ssh directly. This has the disadvantage that they dont get their own xterm and I have to start another xterm manually if I need another one. So I started to looking into aliasing ssh to the same thing. However, aliases arnt clever enough for this you need to use functions instead.

So I wrote a function to do what i wanted.

function ssh {
xterm -T $1 -e ssh $1 &
}

It then occured to me since this is just programming perhaps I can expand this to check to see if host is mentioned in .machines and if it isnt add it. So I wrote a function

function testmachine {
machine=`grep $1 ~/.machines`
if [ "x$machine" = "x" ]
then
        echo "not in ~/.machines adding"
        echo $1 >> ~/.machines
        source ~/.bash_aliases
fi
}

As you can see it also then sources ~/.bash_aliases this makes sure that the current shell gets the new alias. I then added more to the ssh fucntion

function ssh {
xterm -T $1 -e ssh $1 &
testmachine $1
}

I then told my .bashrc to source a new file called .bash_functions which contains the two fucntions from above. And everything is now good.

- Entries from October 2006

Function and Alias use in bash