Lab 4 Reference Document

Part 1: .vimrc and .bash_profile

In the file ~/.bash_profile on ieng6, add:

alias ls="ls --color"

Create the file ~/.vimrc on ieng6, and copy in:

set tabstop=4
set softtabstop=4
set shiftwidth=4
set autoindent
set number

Part 2: Writing a Search Program

(clone the github classroom repo from here: https://classroom.github.com/a/nzV8A2UB)

For this lab, you'll be testing your program on the "rockyou" password list from your PA2, you can copy it over from this path on ieng6:

/home/linux/ieng6/CSE29_FA25_A00/public/pa2/rockyou_clean.txt

You'll be writing "mysearch.c". Your program should take 1 argument (the string to search for). It should read lines from standard input, and print out all of the input lines that contain the search string.

./mysearch PATTERN

You can use the strstr() function to search for a string within another string.

Part 3: Extra Options

Expand your program to handle extra flags: 

./mysearch -n PATTERN : print line numbers before each line

./mysearch -v PATTERN : print only lines that don't contain PATTERN

./mysearch -c PATTERN : don't print pattern matches, just print out the count of matching lines at the end

Each person in your group should implement a different one of these; you'll need all three to do the whiteboard activity.

You can use the strcmp() function to check whether two strings are equal.

Work Check-off

Make sure your program supports at least one of -n, -v, or -c, and commit/push your code.
Make sure you have committed and pushed the code you were working on for your -n, -v, or -c file from the lab activity.

If done early, implement some of the following (in no particular order)

  • Make your program handle all 3 of -n, -v, and -c.

  • Add the option -i, for case-insensitive search (i.e. search -i pattern should match lines containing "Pattern" or "PATTERN")

  • Use ANSI Escape Codes to make your program bold or highlight the matches in every matching line, either always or with a --color option. (more info on Wikipedia)

  • Add the option -A to print extra context after a match, so e.g. search -A 2 pattern would print an extra 2 lines after every match.

  • Add the option -B to print extra context before a match (search -B 2 pattern would print an extra 2 lines before every match.) (Note: to be able to do this in C with the tools we've seen so far, you might need to set an upper limit on how many lines back your program will be able to support)

  • Make your program handle options more flexibly, e.g. it could:

    • be able to handle multiple options simultaneously 

    • accept arguments in any order

    • exit with a help message for unrecognized options (e.g. -f, -o) instead of treating them as search patterns. (Or if you pass it the -h or --help options) 

    • if it sees the option "--",  treat all following arguments as search patterns, even if they start with a "-". (This is how actual command line programs allow you to search for the string "-n" instead of specifying the "-n" option.)

    • allow long versions of options, e.g. --invert-match, --line-number, --count, etc