3.1 The Directory Hierarchy

3.1.1 Describe the Directory Hierarchy
a) What is the root directory?

b) What is the root directory's path name?

c) How does a relative path name differ from an absolute path name?

d) What is the .. directory?

3.1.2 Interpret Absolute Path Names
The path name /etc/passwd is interpreted as: 
The root directory contains the directory etc, 
which contains the passwd file.
Interpret the following path names:
a) /usr/john/../janet
b) ~/directory/
c) ~/janet

3.1.3 Interpret Relative Path Names
Interpret the following path names:
a) books/recipes/../drama
b) ./-o
c) ./../...

3.1.4 Multiple Choice
Assume you have the directories: /pubs/guides/user 
and /pubs/reference/manual
1) What directories are siblings?
a) pubs  and pubs 
b) guides  and reference 
c) user  and manual 

2) What is the parent of the user directory?
a) guides
b) pubs
c) reference

3) What is the child of the reference directory?
a) pubs
b) manual

4) If your current directory is /pubs/guides/user, 
which of the following relative path names refers to /pubs/reference?
a) ./././reference
b) ../../reference
c) ../../../reference

3.2 Rules for File Names

3.2.1 List Name and Path Maximum Lengths
Type the following command: getconf NAME_MAX .
a) What is the result?
b) What does it mean?

Type the following command: getconf PATH_MAX .
c) What is the result?
d) What does it mean?
e) How many directories can be in a path name?

3.2.2 Identify Valid File Names
In your current directory, use file redirection to create files 
with the following names and record your results.

a) supercalifragilisticexpialidocious
b) and/or
c) a\ file
d) /dev/null
e) A
f) a
g) .text.file

3.2.3 List Hidden Files
Use the commands: ls, ls -a, ls -A to view 
the contents of your home directory.

a) What do these commands do?
b) How can you hide a file?

3.2.4 Multiple Choice
Which of the following Characters cannot be included in a file's name?
a) space
b) tab
c) End-Of-Line
d) \
e) /

3.2.5 True or False?
1) A File Name beginning with dot (.) must not contain any other dots.
2) The maximum length of a file name is always 14 characters
3) The getconf command returns information about system limits
4) You can create a file named dot-dot (..)

3.3 Information About Files

3.3.1 List File Information
Use the following listing to answer the questions in this exercise:

-rw-rw-rw-  1  bob  acctg  1039  Mar 15  09:58  back
-r--r--r--  2  jan  acctg   959  Apr  1  01:02  keep
-r--r--r--  2  jan  acctg   959  Apr  1  01:02  save
-rwxrw----  1  bob  acctg   100  May  1  12:15  store
dr-xr-xr-x  2  root wheel   512  Jun  1  1997   zip

a) What command was used to get this listing?
b) Which entry is a directory?
c) What user and group owns the file back?
d) When was the file keep last modified?
e) How many names (links) does the file keep have?
f) If keep has more than one link, which of 
the names is the file's other name?
g) Which entry has gone unchanged the longest?

3.3.2 Recognize Types of FIles
a) In an ls -l listing, what character would indicate a directory?
b) What's the difference between a soft link and a hard link?
c) In an ls -l listing, what does the character 
"l" at the beginning of an entry mean?

3.3.3 True or False?
1) Every user has only one group.
2) You cannot make a hard link to a directory.
3) The ls command can only show one time, the modification time.

3.3.4 Matching
Match the character from the ls -l listing with the file type:
a) Ordinary File		i) l
b) Symbolic Link		ii) d
c) Directory			iii) -
d) Block Special file		iv) b

3.4 File and Directory Permissions

3.4.1 Read File Permissions
Use the following listing to answer the questions in this exercise:

-rw-rw-rw-  1  dana  tech   9129  Mar 13  19:00  grab
-r--r--r--  2  jim   pubs  19026  Apr 21  21:29  hold
-rwxrw----  1  dana  tech  87695  May 17  07:57  invest
dr-xr-xr-x  2  root  wheel   512  Jun  1  1997   zip

a) If you are not users dana, jim or root, and you are not a member 
of tech, pubs, or wheel groups, which file can you change?

b) As in part a), Which file can you not read?

c) As in part a), Can you make zip 
your current directory?

d) If you are not root or a member of the wheel group, can you
create files in the zip directory?

e) Which files can user jim edit?

f) Which files can user jim change permissions?

3.4.2 Understand your Default Permissions

a) If you create a file in a directory with mode 664, 
what are the permissions on the file?

b) What does the umask command do?

3.4.3 Change File Permissions
In your home directory, create the file notebook.txt

Type the following command:
chmod 664 notebook.txt

a) What does ls -l show the permissions to be?

Type the following command:
chmod a-x notebook.txt

b) What does the command do?

Type the following command:
chmod u+x,g+x notebook.txt

b) What does the command do?

d) What command would change the permissions on the file to:
rw-rw-r-- ?

3.4.4 Change Directory Permissions
In your home directory, type the following commands
mkdir workbook.examples
chmod ag=rwx,o=r workbook.examples

a) What does ls -ld show the permissions to be?

Type the following commands
chmod a-x workbook.examples
cd workbook.examples

b) What happens?  Why?

Type the following commands
chmod u+x,g+x workbook.examples
cd workbook.examples

c) What happens?  Why?

3.4.5 True or False
1) You can create a directory you can cd into, 
but not list its contents.
2) When you change permissions on a directory, you also change the
permissions on every file in that directory.
3) You can chmod any file that belongs to your group.

3.4.6 Multiple Choice
1) A file is mode 777.  After a chmod u=rw command,
its file mode is which of the following?
a) 644	b) 766	c) 677	d) 600	e) 776

3.5 Perhaps harder questions

1) On a system where the maximum size of a path name is 4096 characters and
the maximum size of a file name is 255 characters:
	a) What's the largest number of directories in a path name?
	b) What's the smallest?

2) How might you find out whose home directory uses the most space on the system?

3) What are the security advantages of groups?