General point today:  Talk in more depth about things we've been using

Note on typing commands:
	Remember rhythm with special characters
	Keep hands loose, like a bubble under your hand
	Use tab as soon as you can (prevents typos, validates input so far)

A general note on special characters:
	Shell processing may change them!
	echo *

Command line grammar, example:

grep -i note /usr/share/dict/american-english

This will find all lines that contain the word "note" in either case inside the file /usr/share/dict/american-english

Pieces and what they are, using examples from above:
	grep :   The command to run
	-i : A flag, or option.  These set options to commands.
	note : A parameter, or argument.  Input to the command that is not a flag. 
		For grep, this is the thing to search for
	/usr/share/dict/american-english
		Another parameter.  For grep, this indicates the file to search
	How these appear in the manual

Commands typically work like this.

Where to specify in the command line:
	Generally speaking, flags can be specified in any order
		- Not all commands follow this
	Flags can usually be combined ( -i -r should be equivalent to -ir )
	Some flags may require a parameter (-o outfile)
		- In that case, the parameter must follow the flag
		- Sometimes, no space is required (-lpthread)
		- Sometimes, it is used (-l pthread)
	There are short and long options
		- Short:  -r -h
		- Long:  --recursive --help
		- Generally, long options have two dashes

Most commands support -h, -v, --help, or --verbose
	Not all, but it is very common

If commands have a mandatory parameter, they will usually print out usage info without it

Sometimes commands require that flags come before parameters
	Usually this is due to a variable number of parameters
	Can't always count on that, and not all commands with variable parameters require it
	
A programming note:
	These appear as parameters to main in C/C++
		- Example with argc and argv
	In Python, you can import argv
	Generally, if you are writing a command-line tool, you should support flags
	There are libraries to help with that!
		- Example:  Python and argparse
		- For C:  getopt and argp

Lab 2, and the class of problems that grep solves
	How about finding out what frequency each core is running at?
	How often did I put the word "grep" in my notes last time?

The dictionary is in /usr/share/dict
	What words have "note" in them?

Intro to "regular" expressions:  . means any character
	Note that there are a few different regular expression grammars
	How many words are at least 10 letters long?
	How many words have at least two letters before two e's?
	How many have a z followed by two letters followed by a p?
		- Yes, this would be useful for scrabble
	
Isolating things:
	Let's get the ipv6 address from ifconfig with head and tail
		- The main weakness of this:  Length matters!
		- It'll be ok for lab 2, most people did it this way
	An expression with grep:
		- Regular expressions can handle this.  We'll learn a piece today
		- Generally, you can match most anything with these
		- Regular expressions take time and practice to master
		- There is more than one syntax for these

We learned these characters for grep:  . * ^ $
	Go ahead and remember these.

At this point, see a command as an assembly line