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=====unix Keywords=====
====The UNIX Programming Environment: Assembler====

===Definition===
An assembler is a program used for converting instructions written in low-level code into machine level code.

===Demonstration===
Demonstration of the chosen keyword.

<cli>
lab46:~$ touch file.asm
lab46:~$ nasm -f bin file.asm -o file.o
lab46:~$ ls
file.asm
file.o
lab46:~$ 

</cli>

====The UNIX Programming Environment: Linker====

===Definition===
A linker is a program used with a compiler or assembler to provide links to the libraries needed for an executable program.

===Demonstration===
Demonstration of the chosen keyword.

<cli>
lab46:~$ ld -o fileA hello.o
lab46:~$ ls
lab46:~$
fileA
hello.o
</cli>

====Filtering====

===Definition===
A piece of software that processes text, for example to remove unwanted spaces or to format it for use in another application.

===Demonstration===
Demonstration of the chosen keyword.

<cli>
lab46:~$ touch apple.txt
lab46:~$ vi apple.txt
<cli>

core 
worm seed
jewel
</cli>
lab46:~$ cat apple.txt

core 
worm seed
jewel

lab46:~$ cat apple.txt | sed -e "s/e/WWW/"
corWWW
worm sWWWed
jWWWwel

lab46:~$ cat apple.txt | sed -e "s/e/J/g"
corJ
worm sJJd
jJwJl
</cli>

====The UNIX Programming Environment: Source Code====

===Definition===
A source code is a text listing of commands to be compiled or assembled into an executable computer program.

===Demonstration===
Demonstration of the chosen keyword.

<cli>
lab46:~$ cat helloC.c
/*
 * helloC.c - a simple "Hello, World!" in C.
 *
 * To compile: gcc -o helloC helloC.c
 */

// include standard I/O functions
//
#include <stdio.h>

// main() function
//
int main()
{
 puts("Hello, World!\n");
 return(0);
}

lab46:~$
</cli>

====Pattern Matching====

===Definition===

 Act of checking some sequence of tokens for the presence of the constituents of some pattern
===Demonstration===
. Match any character 

 * Match 0 or more of the preceding 

 ^ Beginning of line or string 

 $ End of line or string 

 [ ] Character class - match any of the enclosed characters 

 [^ ] Negated character class - do not match any of the enclosed characters 

 \< Beginning of word 

 \> End of word
<cli>
lab46:~$ grep ^[b-d][aeiou] /etc/passwd
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
lab46:~$</cli>

====Security====

===Definition===
Procedures followed or measures taken to ensure safety
===Demonstration===

<cli>
lab46:~$ id tedmist1 (username)
uid=5763(tedmist1) gid=5000(lab46) groups=1730(unix),5763(tedmist1),5000(lab46)
</cli>

====The UNIX Programming Environment: Library====

===Definition===
A library is a collection of subroutines or classes used to develop software.

===Demonstration===
**ar(1)** - Maintain portable archive or library.

<cli>
lab46:~$ ar cq lib.a *.o
lab46:~$ ls
lib.a
</cli>

===Syntax===
**ar** [arguments] [ posname ] archive file.  - Arguments can be found in the man pages of ar. Use man ar.
>>
**Some arguments include:**
>>
- c: create a new library  
>>
- q: add the named file to the end of the archive  
>>
- r: replace a named archive/library member  
>>
- t: print a table of archive contents  



====Regular Expressions====

===Definition===
Regular expressions, also referred to as regex or regexp, are search criteria for text pattern matching that provide more flexibility than simple wild-card characters.

===Demonstration===

**These Regular Expressions are as follows:** 
 
  - .  Match any character  
  - *  Match 0 or more of the preceding  
  - ^  Beginning of line or string  
  - $  End of line or string  
  - [ ]  Character class - match any of the enclosed characters 
  - [^ ]  Negated character class - do not match any of the enclosed characters  
  - \<  Beginning of word  
  - \>  End of word  


<cli>
lab46:~$ grep ^[b-d][aeiou] /etc/passwd
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
lab46:~$
</cli>

=====unix Objective=====
====Understanding And Use Of Pattern Matching====

===Definition===
Pattern matching is making use of a pattern, usually a regular expression, and trying the pattern various ways on a string to see whether there's any way to make it fit.

===Method===
The method of measurement will be the understand and how to successfully incorporate pattern matching expressions, such as the ones below. 

===Measurement===
Follow your method and obtain a measurement. Document the results here.
. Match any character 

 * Match 0 or more of the preceding 

 ^ Beginning of line or string 

 $ End of line or string 

 [ ] Character class - match any of the enclosed characters 

 [^ ] Negated character class - do not match any of the enclosed characters 

 \< Beginning of word 

 \> End of word

>> By understanding and incorporating these expressions, you can successfully search through a file with ease to get a desired result.
===Analysis===
Reflect upon your results of the measurement to ascertain your achievement of the particular course objective.

* How did you do?

>> Work in progress, as of right now, I am still learning how to use these.
* Is there room for improvement?

>> Yes.
* Could the measurement process be enhanced to be more effective?

>> In time, and the usage of these will making the learning of pattern matching that much easier.
* Do you think this enhancement would be efficient to employ?

>> Yes it would be efficient to employ when searching through a file for a desired result.

* Could the course objective be altered to be more applicable? How would you alter it?

>> No the course object is applicable to a student, such as I, situation involved Unix.
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