Oh okay, I though it was a kind of magic that can occur by tweaking the $SHELL ^^

I actually wrote a tool (ptti, see above) that get text from the user, and write it to a fifo named 'in' in the current directory. So I get an interactive prompt to write message (prepending everything with 'send' or 'echo' can be painfull...).

I also improved it to navigate between multiple fifo, but it's still quite buggy.