15. The 3 UNIX file permissions (rwx) are assigned to three defined categories of users. The categories are: a. owner, friend, group b. owner, friend, other e. friend, subgroup, group d. owner, group, other 16. In the case of directory permissions, the symbol "x" indicates that a given category of user can: a. read the content of the directory b. create/delete files of the directory c. "go through the directory 1. Non of the above 17. What will be the displayed value if we run the commands "value='expr 1 + 1"; echo $value" a. 1 b2 c. O d. Non of the above 18. The "f test -d filel" command line tests to see: a. filel exists and is a directory? b. filel exists and is executable?! c. filel exists and is not a directory? d. filel exists and is no longer than 0 bytes? a Tine Debbie GIUD