I hate to do this (Sorry Staz) but for anything to do with UNIX I'd reccommend RealBASIC.  This requires MacOS X.

Here is a simple RealBASIC shell program
this one lists files, but you can change 
it in s.execute to whatever unix command you want.

Dim s As Shell
s=New Shell
If TargetCarbon then
s.execute "ls -la"
If s.errorCode=0 then
EditField1.text=s.result
else
MsgBox "Error Code: "+Str(s.errorCode)
end if
end if

-Brian