Sometimes a script wraps a command, and a script must have its interpreter's right absolute path after #! on the first line, see man execvp(): Man Page for execvp (opensolaris Section 2) - The UNIX and Linux Forums If the interpreter path is wrong, you get this sort of error. Do a 'which enable', do a file command on that file, and if not an object file, look at the file. One script enable may call another enable using the #! line.