====== AWK - BEGIN and END ======

Actions can be specified to take place prior to the actual start of processing or after it has been completed with **BEGIN** and **END** statements respectively.

  * **BEGIN** statements are most commonly used to establish variables or display a header.
  * **END** statements, on the other hand, can be used to continue processing after the program has finished.


----

Assuming a file, **test.txt**, exists with the following contents:

<file>
10   Peter     Terence   Roux        45
11   Virginia  Genevieve  Roux       45
12   Felix     Devon     Roux         5
13   David     Bruce     Stevenson   48
14   Bob       James     Smith       16
48   Adam      Winter    Ridley      23
</file>

----

===== Basic BEGIN Statement =====

Issue the following command:

<code awk>
awk 'BEGIN {print "NUMBER ITEM QUANTITY PRICE"}' test.txt
</code>

returns:

<code>
NUMBER   ITEM   QUANTITY   PRICE
</code>

----

This would be more useful when run as:

<code awk>
awk 'BEGIN {print "NUMBER ITEM QUANTITY PRICE"}{print NR,$1,$2,$3}' test.txt
</code>

returns:

<code>
NUMBER ITEM QUANTITY PRICE
1 10 Peter Terence
2 11 Virginia Genevieve
3 12 Felix Devon
4 13 David Bruce
5 14 Bob James
6 48 Adam Winter
</code>

<WRAP info>
**NOTE:**  

  * The **BEGIN** has allowed the header to be added to the output.
  * The **NR** variable used in the 2nd print numbers each line.  It is a built-in variable of AWK.

</WRAP>

----


===== Basic END Statement =====

Assuming a file, **test2.txt**, exists with the following contents:

<file>
pens      10    1.99
pencils   20    3.99
staplers   5    8.99
rulers    12    2.50
</file>

Issue the following command:

<code awk>
awk '{x=x+($2*$3)} END {print "Total Value of Inventory: "x}' test2.txt
</code>

returns:

<code>
Total Value of Inventory: 174.65
</code>

----

This would be more useful when run as:

<code awk>
awk '{x=x+($2*$3)} {print $1,"QTY: "$2,"PRICE:"$3,"TOTAL: "$2*$3} END {print "Total Value of Inventory: " x}' test2.txt
</code>

returns:

<code>
pens QTY: 10 PRICE:1.99 TOTAL: 19.9
pencils QTY: 20 PRICE:3.99 TOTAL: 79.8
staplers QTY: 5 PRICE:8.99 TOTAL: 44.95
rulers QTY: 12 PRICE:2.50 TOTAL: 30
Total Value of Inventory: 174.65
</code>

<WRAP info>
**NOTE:**  

  * The **END** has allowed a total line to be added to the output.
      * It is only run at the end.

</WRAP>

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