This grep or egrep(just grep with no -E flag), will return all sentences that begin with a capital letter and are followed by any 
number of uppercase letters, followed by lower case letters, followed by blank spaces and end with a period.
This is an example of an extended regular expression, which allows for the use of the :alpha: :upper: :lower: etc. meta search criterion.

The '' delineates the beginning of an expression so that the meta characters are not interpreted by bash as commands.
The carat symbole ^ represents that the beginning of the expression MUST begin with, in this case an uppercase character.
It is encapsulated by two square brackets [[]] so as to delineate as ingle character, which then MUST be followed by ANY
number of uppercase characters, lowercase characters, and empty space characters, the ANY condition is inputted by the asterix * metacharacter

The backslash breaks us out of extended regular expressions and then returns us to LITERAL or BASIC regular expressions. In this case
we MUST follow it by a literal period .

We then ask it to search the lorem.txt using the regular expression, which will give us (roughly) every sentence within the text.
Note that this is FAR from perfect however, you can even see its major issues by using the same command on this document instead of lorem.txt

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grep -E '^[[:upper:]][[:upper:][:lower:] ]*\.' lorem.txt

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some text unique to grep2(compare these two files using the comm and diff(-u) commands)

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(this file was copied from grep 1, and originally showed 'unique to grep1' above, it was then passed through the diff command thusly:

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diff -Naur grep_notes_1.txt grep_notes_2.txt > grep_patch.txt

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This created a grep_patch.txt file that you can see logs the output of the diff command, using the patch command, we can pass this
file through the command to update our original grep_notes_1.txt file to change ONLY what is different from the two files.
In this case, grep_notes_2.txt is considered the UPDATED file, and will thusly change the grep_notes_1.txt file.  It could just as easily
be used to DOWNGRADE the file by reversing the order.  This is useful for software development/updating/downgrading versions of programs.)

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patch < grep_patch.txt

Outputs$:patching file grep_notes_1.txt
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