March 10th Notes

Reviewing Useful Tools For UDR1
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1. dd
2. bc - Binary Calculator ( CTRL + D - Exit)
3. du
4. bash shell scripting
5. od - Octal Dump
6. hexedit - Hex Editor, Displays Information
7. bvi - Binary VI

Bash + BC
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echo "2+2" | bc --> 4
a =`echo "2+2" | bc` --> A is now 4
bc -q --> Doesn't display banner
bc -l --> Adds decimal points

Advanced BC
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ibase=16 --> Changes input base to 16 --> Output remains Decimal
obase=2 --> Changes output base to 2 --> Output is now 2 (Binary)
echo "2^64" | bc | wc -c --> Total size of an input 64-bits can hold

bc --> Great for calculations
dd --> Great for file surfing (Backing-up)

Regular Expressions (RegEx) - grep
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										|
. match any single character			|
[] match any one of enclosed			|
[^] do not match any one of enclosed	|
\^ match start of word					|	Basic
\> match end of word					|	RegEx
^ match start of line					|
$ match end of line						|
* 0 or more of the previous				|
										|
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Extended Grep - egrep
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\( \) 	GROUP							| Extended
|		OR								| RegEx
----------------------------------------

More RegEx
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cat words | grep '^...$' | wc -l --> Displays all words with 3-characters
cat words | grep '^.[aeiou].[aeiou]$' | wc -l --> Displays 4-characters 2 and 4 are vowels
cat words | grep '^[listOfLetters][repeat]$' | wc -l --> Displays characters for that length in Scrabble
cat words | grep '^[listOfLetters]*$' | wc -l --> Displays any length with those letters inside of it