CS 742 - Compress files

    1. This is an example of using a Huffman code to compress a file.
       We start by creating a file called "tempfile":

$ ls -l tempfile
-rw-r--r--    1 chang    csprof        165 Dec  3 22:47 tempfile

$ cat tempfile
aaaaaaaaaa
bbbbbbbbbb
bbbbbbbbbb
cccccccccc
cccccccccc
cccccccccc
dddddddddd
dddddddddd
dddddddddd
dddddddddd
eeeeeeeeee
eeeeeeeeee
eeeeeeeeee
eeeeeeeeee
eeeeeeeeee

Note that the file contains: 10-a's     
                             20-b's
                             30-c's
                             40-d's
                             50-e's
                             15-<line feed characters> that you can't see.

That is a total of 165 bytes.

    2. Next, execute the gzip command to create a compressed file
       called tempfile.gz.

          $ gzip tempfile

    3. Check the size of the new file:

$ ls -l tempfile.gz
-rw-r--r--    1 chang    csprof         51 Dec  3 22:47 tempfile.gz


    4. Now, use a hex dumper to inspect the compressed file:

$ hexdump -C tempfile.gz
00000000  1f 8b 08 08 e2 88 ed 3d  00 03 74 65 6d 70 66 69  |.......=..tempfi|
00000010  6c 65 00 4b 4c 84 01 ae  24 38 40 66 26 c3 01 0e  |le.KL...$8@f&...|
00000020  66 0a 1c 10 66 a6 c2 01  49 4c 00 64 ab f9 8e a5  |f...f...IL.d....|
00000030  00 00 00                                          |...|
00000033

    5. Uncompress the file using gunzip
  
$ gunzip tempfile.gz