=====unix Keyword 2=====
pipes

====Definition====
In Unix, a pipe (or pipeline) is used to direct the flow of output from one command as input to another command. This can be used to connect two operations together on a single command line, instead of having to use multiple command line inputs to receive the same result.  

In Unix systems, pipes are shown using a vertical bar symbol, |.  This bar will take the output from the command on the left, and use it as the input for the command on the right.

An example of this would be:
<cli>
who | grep $USER
</cli>
This would execute the who command, and then use it as input to the grep command, which would parse who for all instances of your own username.

====References====

  * [[http://en.wikipedia.org/wiki/Pipeline_(Unix)]]


=====unix Keyword 2 Phase 2=====
escape character

====Definition====
An escape character is a character used to invoke an alternative interpretation of subsequent characters in a sequence. This is generally used when a character on it's own has a specific function. 

An example of this (in bash) would be the * wildcard, which is used to expand a name.  If a * is needed as a literal character ("*" as opposed to *), an escape character is needed to tell the * not to act as a wildcard.  In bash, the escape character is a backslash.  Typing \* would treat * as a character, instead of a wildcard.
====References====

  * http://en.wikipedia.org/wiki/Escape_character
====Demonstration====
For my demonstration, I'm going to create a few files using symbols which require escape characters, and then show how the escape characters must be used to access these files.

The files I created were named "$$$", "***", "???", and "\\\"

{{:opus:fall2012:smeas:keyword_2_01.png?direct&200|}}

Attempting to access these files by typing in just their names caused different things to happen for each file, based on what the purpose of that file's character was.

{{:opus:fall2012:smeas:keyword_2_02.png?direct&200|}}

However, if the bash escape character ("\") was used before each character in the files' names, they were treated as a regular character, instead of a special character.

{{:opus:fall2012:smeas:keyword_2_03.png?direct&200|}}

(I also realized right after taking and uploading these screenshots, I made my demonstration in my Experiment 2 folder on accident. Whoopsie!)