HW 3: Bash Scripting

HW 3: Bash Scripting

Overview: The last homework had you create a pipeline of utilities to locate files with the same content.
This homework will have you perform this task again using features of bash.
Objective: Write a bash program that finds all the files with the same md5sum hash, sorts them by
the size of the group sharing that hash, and prints out the groups as a comma-separated list.
Guidelines:
• You must do this by splitting the program into three functions:
– The first function, find_and_count_duplicates , will be for listing the files (find), determining
their md5sum (md5sum), and creating a few arrays. One array will map the hash to all the files
that have that md5sum. Another array will store a count of the number of duplicates for each
md5sum.
– The second function, assign_md5sums_to_group_sizes , will have you create an array that will
store all the md5sum hashes for a single group size.
– The third function, print_group_sizes , will be to iterate over the group sizes, and print the
files for each md5sum group of that size.
• You must comment some of your code in each function (use # before text).
• You must use at least one for loop and at least one while loop.
Restrictions:
• No credit will be given if you use the method from solution 2.
• The only commands you are permitted to use outside of bash’s builtin functionality are find, md5sum
, sort, and tr (once each).
Helpful hints:
• Command substitution is one way of initializing an array
• To use a parameter as the key of an associative array, you will need to quote that variable.
• Printing after each step to diagnose problems early on. Colorizing the input can also help you debug.
Bonus 1: Use the ANSI escape codes to print out in color. This will make output much easier to read.
Hint: These look like
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# Regular Colors
Black='\033[0;30m' # Black
Red='\033[0;31m' # Red
Green='\033[0;32m' # Green
Yellow='\033[0;33m' # Yellow
Blue='\033[0;34m' # Blue
Purple='\033[0;35m' # Purple
Cyan='\033[0;36m' # Cyan
White='\033[0;37m' # White
Bonus 2: Print out the directory of the files in one color, and the actual filenames in another color.
Bonus 3: Is this faster or slower than the first homework 2 solution? Compare the time taken for both on
different numbers of unique files using the time command. Test for 5000 unique files, 20000 unique files, and
50000 unique files. You may use the command:
for i in `seq <filecount`; do echo $i $i; done
to create unique files.
Submission:
Upload a single text file (.txt) containing all of your answers to Canvas by the due date.
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