CST8177 - Lab 3 Review 2

Objectives

• To review command line features, file system access, and permissions

Lab Outcome

• A review of working with the command line

• A review of basic Linux utilities

Additional Notes

• If you are uncertain as to how to proceed or have any problems, refer to class notes from previous for more information, your textbook, and the man pages.

In-Lab Demo: Create a new non-empty file with both a hard link and a soft link.

Exercise #1: Working with the find command

Hint: Use the -mount option to prevent searching mounted file systems like /proc and /dev.

Execute the command used to find all files from / with an extension of cron

[user1 @localhost ~] $ __________________________________________

______________________________________________________________

Execute the command used to find all files belonging to user1

[user1 @localhost ~] $ __________________________________________

_______________________________________________________________________________

Execute the command used to find all files belonging to the user of uid 500.

[user1 @localhost ~] $ __________________________________________

______________________________________________________________

Execute the command used to find all files that have been modified within the last 3 days (there's a trick for past and future):

[user1 @localhost ~] $ __________________________________________

______________________________________________________________

Exercise #2: Working with links

Create a small non-empty file named target

[user1 @localhost ~] $ _______________________________________

Create a directory named temp.

[user1 @localhost ~] $ _______________________________________

Go into the temp directory.

[user1 @localhost ~] $ _______________________________________

Working with soft links

Create a soft link to the file target named s-link.

[user1 @localhost temp] $ ____________________________________

Test that you can read the file target using the soft link s-link.

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

Display both files, target and s-link, including all file attributes and the inode number.

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

What is the first difference between the two entries?

______________________________________________________________

Change permissions of the file target to give no access to others.

[user1 @localhost temp] $ ___________________________________

Display both files, target and s-link, including all file attributes and the inode number.

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

What, if anything, has changed in s-link?

______________________________________________________________

Rename the file target to new-target.

[user1 @localhost temp] $ ____________________________________

Test that you can read the file new-target using the soft link s-link.

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

Briefly explain why this behaves as it does:

______________________________________________________________

Rename the file new-target to target.

[user1 @localhost temp] $ ____________________________________

Working with hard links

Create a hard link to the file target named h-link.

[user1 @localhost temp] $ ____________________________________

Test that you can read the file target using the hard link h-link.

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

Display both files, target and h-link, including all file attributes and the inode number.

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

Are the file attributes, except for the filename, identical? Record any difference

______________________________________________________________

Change permissions on target to give no access to the group owners and full access to others.

[user1 @localhost temp] $ ____________________________________

Display both files, target and h-link, including all file attributes and the inode number.

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

Are the file attributes, except for the filename, identical? Record any difference

______________________________________________________________

Rename the file target to n-target.

[user1 @localhost temp] $ ____________________________________

Test that you can read (cat) the file n-target using the hard link h-link.

[user1 @localhost temp] $ ____________________________________

______________________________________________________________

Remove the file n-target. , and both links s-link and h-link

[user1 @localhost temp] $ ____________________________________

Exercise #3: Working with file permissions

Show the command and circle the practical minimum permissions required to successfully complete the actions listed below.

To produce a detailed directory listing (ls -l) within a directory, the user requires for that directory:

[user1 @localhost ~] $ ___________________________________

R W X

To go into a directory, the user requires for that directory:

[user1 @localhost ~] $ ___________________________________

R W X

To create a file or subdirectory into a directory, the user requires for that directory:

[user1 @localhost ~] $ ___________________________________

R W X

Show the command and circle the practical minimum permissions required to successfully complete the file manipulation actions listed below.

To copy a file the user requires:

for the source directory:

[user1 @localhost ~] $ ___________________________________

R W X

for the target directory:

[user1 @localhost ~] $ ___________________________________

R W X

for the file:

[user1 @localhost ~] $ ___________________________________

R W X

To move a file the user requires (assume the same filesystem for both source and target directory):

for the source directory:

[user1 @localhost ~] $ ___________________________________

R W X

for the target directory:

[user1 @localhost ~] $ ___________________________________

R W X

for the file:

[user1 @localhost ~] $ ___________________________________

R W X

To move a file the user requires (assume different filesystems for source and target directory, perhaps a USB stick and the hard disk):

for the source directory:

[user1 @localhost ~] $ ___________________________________

R W X

for the target directory:

[user1 @localhost ~] $ ___________________________________

R W X

for the file:

[user1 @localhost ~] $ ___________________________________

R W X

Briefly explain the differences between moving on the same and on different filesystems:

______________________________________________________________

______________________________________________________________

______________________________________________________________

To delete a file the user requires:

for the directory:

[user1 @localhost ~] $ _______________________________________

R W X

for the file:

[user1 @localhost ~] $ _______________________________________

R W X

Exercise #4: Working with default permissions

Viewing default permissions

Login as user1.

Type umask and record the output of the command:

[user1 @localhost ~] $ _______________________________________

______________________________________________________________

Based on the user file-creation mask as displayed by umask, determine the default permissions for directories and files in octal mode:

File: ___________________

Directory: ___________________

Verify it by creating a new file and displaying its long entry.

[user1 @localhost ~] $ _______________________________________

[user1 @localhost ~] $ _______________________________________

________________________________________________________________________

Record the default permissions set on the file in symbolic mode:

______________________________________________________________

Record the default permissions set on the file in octal mode:

______________________________________________________________

Verify it by creating and displaying a new directory.

[user1 @localhost ~] $ _______________________________________

[user1 @localhost ~] $ _______________________________________

______________________________________________________________

Record the default permissions set on the directory in symbolic mode:

______________________________________________________________

Record the default permissions set on the directory in octal mode:

______________________________________________________________

Changing default permissions

Set the user file-creation mask to 077.

[user1 @localhost ~] $ _______________________________________

Type umask and record the output of the command:

[user1 @localhost ~] $ umask

______________________________________________________________

Based on the bitmask, as displayed by umask, determine the default permissions for directories and files in octal mode:

File: ___________________

Directory: ____________________

Verify it by creating a new file.

[user1 @localhost ~] $ _______________________________________

[user1 @localhost ~] $ _______________________________________

______________________________________________________________

Record the default permissions set on the file in symbolic mode:

______________________________________________________________

Record the default permissions set on the file in octal mode:

______________________________________________________________

Verify it by creating a new directory.

[user1 @localhost ~] $ _______________________________________

[user1 @localhost ~] $ _______________________________________

______________________________________________________________

Record the default permissions set on the directory in symbolic mode:

______________________________________________________________

Record the default permissions set on the directory in octal mode:

______________________________________________________________