ecos on niosii

It seems that you've got yourself tied in a bit of a knot with this one!

You need to make sure that the user tools path is set to the default value configured by the installer. If you have any doubt about whether this is the case, you should reinstall ecos.

Having done this it's important to make sure that you launch nios2configtool from within an SDK shell from the Nios II 1.0.1 kit rather than from a regular bash shell. The sed problem you are describing is caused by an incorrectly configured path. The path should be configured correctly by default from with an SDK shell.

If your problem persists, then check that you don't have a conflicting version of cygwin installed on your machine. That may be causing you problems.