Review

Last Week

What did we do in our last class?

Special Symbols for Paths

What symbols represent the following directories? →

• the current directory
• up one directory (parent directory)
• up two directories
• root directory
• home directory
• directory you were previously in

Special Symbols for Paths

• . (dot) - the current directory
• .. (dot dot) - up one directory (parent directory)
• ../.. (dot dot slash dot dot) - up two directories
• / (slash) - root directory
• ~ (tilde) - home directory
• - (dash) - directory you were previously in

Root

• What’s the root directory? →
• What symbol represents it?? →

Note About Root

We didn’t explicitly mention this in the last class, but:

• the root directory is not writable by the lab computer default user account
• consequently, if you’re in root, commands like mkdir, touch, etc… should fail
• How would I get to root again? →

Absolute Paths

What’s an absolute path?

Relative Paths

What’s a relative path?

Relative and Absolute

Tell me how to create these directories in my home folder →

• a directory called myprojects
• within that, two directories called lab1 and lab2
• and finally, in lab1, create a directory called output

This should result in:

• myprojects
• myprojects/lab1
• myprojects/lab2
• myprojects/lab1/output

Relative and Absolute Path Questions

1. From /Volumes, change to the lab1 directory that was just created
   • In /Volumes: cd ~/myprojects/lab1
2. From home directory, what’s the relative path to output?
   • In home: myprojects/lab1/output
3. From home directory, what’s the absolute path to output?
   • In home: /Users/professor/myprojects/lab1/output
4. From output, what’s the relative path to lab2?
   • In myprojects/lab1/output: ../../lab2

Relative and Absolute Path Questions Continued

1. From output, what’s the absolute path to lab2?
   • In myprojects/lab1/output: /Users/professor/myprojects/lab2
2. From lab2, what’s the relative path to output?
   • In lab2: ../lab1/output
3. From lab2, what’s the absolute path to output?
   • In lab2: /Users/professor/myprojects/lab1/output

Reviewing input/output Commands

• How do I print/output text to the screen? →
  • echo [text]
• How do I clean up / remove the text from the screen? →
  • clear

Downloading Files

• How do I download a file and display its contents on my screen with one command? →
  • curl someurl.com
• How do I download a file and save it to a file with a specified name? →

Archiving and Compressing Files

• How do I archive an entire directory into a single file? →
  • tar -cvf archivename.tar dirname
• How do I compress a file? →
  • gzip filename

Extract and Uncompress

• How do I uncompress a zip (.zip) file? →
• How do I extract files from a compressed archive (.tar.gz)? →

Activity: Drills!

Entering commands flash cards x 3 (use set 2)

We’ll do this together, then try downloading it yourself:

1. Download drills.py to the home directory
2. Type python drills.py
3. When prompted for a number, enter 2
4. CTRL-C quits

Summary Part 1

(brackets - []’s - denote arguments that you must supply; the brackets are not part of the command, so don’t type them out)

• echo [something to print to the screen]
• clear
• curl [url of file to downlaod]
• curl -o [name of file to download to] [url of file to download]
• unzip [name of file to unzip]
• tar -xvf [name of file to extract and uncompress]
• tar -cvf [name of archive] [name of directory to archive]
• gzip [name of file to compress]

Lab

Review

• Type each command (with arguments and flags) exactly
• Only press <ENTER> when instructed…
• <TAB>, <ENTER>, <UP>, <DOWN> are the actual keys!
• Paste answer or output below the dashed line (————)

Activity: Everything We’ve Learned So Far

Entering commands flash cards x 3 (use sets 1 and 2)

We’ll do this together, then try downloading it yourself:

1. Download drills.py to the home directory
2. Type python drills.py
3. When prompted for a number, enter 12
4. CTRL-C quits

Working With Files