1. In directory 'zahrada' create directory 'kompost' (compost:), where any member of group 'zelenina' can write (and no one more), but any user can delete only files created by him/her. 2. Do you remember (mrkva) carrot, (kapusta) cabbage and their common (zahrada) garden? ;) Could you attain, that (from point of view of 'mrkva' and 'kapusta') if 'mrkva' creates some file or subdirectory in 'zahrada', 'kapusta' will be able to work (read from it, write to it) with it as well (and also vice versa)? We assume that both 'mrkva' and 'kapusta' won't be malicious and will not try to intentionally deny the access -- they will simply use system the usual way (e.g. they execute 'mkdir /home/zahrada/kukurica' (kukurica = corn), ...). 3. Create user 'hrach' (pea), which will be able to change contents(!) of "secret" foliovnik (greenhouse) from previous exercises without knowing its name, but he will not have access to any other contents of directory 'zahrada'. Be sure that 'hrach' can change its content even if 'mrkva' or 'kapusta' rename it and 'hrach' will not know the new name. 4. Users 'mrkva' and 'kapusta' are lazy to always write '../zahrada' to get to files in directory 'zahrada'. Make it easier! 5. In 'zahrada', create device called 'hadica' (slovak name for 'hosepipe', which suggests that it should be a UNIX pipe:). Start reading it in one terminal, and in another one write something to it. Also, find out, what happens, if two processess want to write to one pipe at the same time, or two processes try to read it (again, at the same time). 6. Have a look into directory /proc and see, what useful information about system you can find out. Most of files in there are text files, so you can read them directly. Hint: File named 'kcore' is not that much suitable for reading. Believe us, your colleagues from earlier exercises found it out the hard way:).