Piping commands from the network may be a bad idea, but I pipe to my shell locally all the time. The idea is that you write a shell loop that prints a bunch of commands using `echo` and then once the commands look right, you pipe them to `sh -v`. It's great for the exact opposite reason piping from the network is awful: you can see what you're about to execute before you execute anything – I don't trust myself to write complicated shell loops without seeing what I'm about to run first.
Piping commands to a shell will subject your (probably already completely specified) command names and argument to all sorts of modifications: brace expansion, tilde expansion, parameter and variable expansion, command substitution, arithmetic expansion, word splitting, and pathname expansion.
I never do that; If I need a trial loop, I do the loop with all the relevant commands prepended by "echo" (and every ";", "&", "&&", and "||" properly escaped).
Yes, that's the point. You print the commands as you would type them manually, make sure they look right and perhaps test a single one out. Then you can pipe that whole thing into another shell. It's even reasonable to generate shell commands from, say, perl. Rather than having perl call system, just have perl print each command and then pipe the output of the whole thing to `sh -v`.
