the parent process does not wait correctly. You can try this for example
with a "sleep 5" in the commands. It should wait 5 seconds.
The problem is, that you start i processes, but you wait only for i-1.
So the parent does not wait for the last child.

You can change the value that you pass to i, are you can also get rid of
this length parameter.
Instead of counting the children and using a for loop in the wait
function, you could use a while loop, that calls wait as long as it
returns not -1. The function wait always waits until any child is closed
and returns the PID of a child. If there is no child process to wait
for, it directly returns -1.


Another thing is, that it would be better to only skip a command with
too many parameters, instead of calling exit and stopping the complete
program.


Andreas