CSCI 57 and 65: Introduction to Unix Courses

Laboratory Assignment 8

ASSIGNMENT DUE: see calendar on the web

• On all homework please include
• Your Name
  
• Course Number
  
• Date
  
• ecst login name
  

• The preferred format for homework for the rest of the semester (unless otherwise specified) is to just print it out the lab webpage and write your answers on the printout. 
  
• If you are really into typing I will still take it typed.
  
• You do NOT need to include the printing cover page (details given in lab).
• You do NOT need to print from Unix.
  

• This lab will use the utilities tar, gzip, gunzip, md5sum, bzip2, bunzip2, compress, zip
• Here is a simple formula [percent reduction] = 100 - ( [compressed file size]/[orginal file size] * 100 )
  
• Please answer the following questions (answers and/or help given in lab). 
  

• Questions
1. Copy the lab8 directory from /user/s/toddj/lab8 to your home directory.
1. Use the command cp -r /user/s/toddj/lab8 ~
2. What does the -r option do (read the man page for cp if unsure)? _______________________________________
3. You should now have a directory in your home directory named "lab8" and it should have 4 files in it: gpl.txt, lgpl.txt, image.jpg, and logo.gif.
4. Run ls -l in this directory, the forth column is the file size.  If you have ls aliased to the the -h option you should unalias it (type, unalias ls ) so that you get the file size in bytes instead of kilo-bytes.  You should see 18009 for gpl.txt.
5. Next you will use the commands gzip, gunzip, compress, uncompress, bzip2, and bunzip2 as discussed in class. All of these commands have a -v option that will help make your life easier.
   
   
2. Complete the following table (all sizes in bytes, not kilobytes, megabytes, etc):
   
   

   Filename	initial file size size	size after using gzip	% reduction with gzip	size after using compress	% reduction with compress	size after using bzip2	% reduction with bzip2
   gpl.txt	18009	6858	62%
   image.jpg
   lgpl.txt						8339	68%
   logo.gif				8558
   Total	64226	35433	45%

   
   In the total row, don't use addition to get the percentage columns,
   instead calculate it from initial size total and compressed size total.
   For example, 45% = 100 - ( 35433/64226 * 100 )
   For example, [total % reduction with compress] = 100 - ( [total size after using compress] / 64226 * 100 )
   
   Running the Following Commands in order will help you complete the table:
   
• ls -l
• gzip *
• ls -l
• gunzip *
• ls -l
  
• compress -v *
• ls -l
  
• uncompress *
• ls -l
  
• bzip2 *
• ls -l
• bunzip2 *
• ls -l
  
  
3. Based on the information in the table above. Answer the following questions:
1. What tool gives the best compression? ________________________________________
2. What tool gives the poorest compression? _____________________________________
3. What file type did compression work the best on? _______________________________
4. What file type did compression work the worst on (smallest percent reduction)? ______________________________
   
   
4. Comparing gzip'ed tarballs and zip compression, peform the following steps while filling out the table below
   
1. Create a tar ball of the 4 files, tar cvf mybackup.tar gpl.txt image.jgp lgpl.txt logo.gif
2. Try compressing the tar ball with gzip
   
3. Try compressing the tar ball with compress
   
4. Try compressing the tar ball with bzip2
   
5. Create a zip file of the 4 files, zip mybackup.zip gpl.txt image.jgp lgpl.txt logo.gif
   (NOTE: You can not just run these commands in order, you have to uncompress things and use ls -l )
   
   

   Backup	File size in bytes
   mybackup.tar
   mybackup.tar.gz
   mybackup.tar.Z
   mybacup.tar.bz2
   mybaxkup.zip



5. What files are in the backup /user/s/toddj/lab8-backup.tar.gz ?
1. _____________________________________
2. _____________________________________
   
   
6. What is the md5sum of /user/s/toddj/lab8-backup.tar.gz (32 characters long, give the last few)? ____________________________________
   
   
7. Write your first bash function, add the following to your .bashrc file.
   
   

   # ecd - easy cd function (or enhanced cd function) ecd () {       cd $1       echo "Your New Directory is `pwd` "       echo "Here are the files this directory contains, numbered in order"       ls | nl       echo "I hope you are having a nice `date +'%A'`" }

   
   Next, source your .bashrc, type source .bashrc to pickup the change.
   Now you can use ecd just like you used to use cd