65 lines
1.8 KiB
HTML
65 lines
1.8 KiB
HTML
---
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layout: page
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category-page: scripts
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category-title: Scripting
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tags: loop for done script scripting
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author: Matteo Omenetti
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title: For Loop
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---
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<!-- Introduction -->
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The second type of loops are for loops.
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They follow this syntax:
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{% highlight bash %}
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for [variable] in [list] do
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[code]
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done
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{% endhighlight %}
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Their purpose is to <i>iterate</i> over a list. Also, while loops could do this,
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you might argue... <br>
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Of course, they could, but for loops are specifically meant to do this. Therefore, for instance,
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you don't have to declare your counter variable outside the loop. Most importantly,
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this variable can be accessed from inside the loop. <br>
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For loops take this form:
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{% highlight bash %}
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for VARIABLE in 1 2 3 4 5 .. N
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do
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command1
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command2
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commandN
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done
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{% endhighlight %}
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<!-- End of Introduction -->
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<!-- First Example -->
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Here is a simple example:
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{% highlight bash %}
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for i in 1 2 3 4 5
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do
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echo "Welcome $i times"
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done
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{% endhighlight %}
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This first example of code simply displays a welcome message 5 times.
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The output of this piece of code is:
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<pre>
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Welcome 1 times
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Welcome 2 times
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Welcome 3 times
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Welcome 4 times
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Welcome 5 times
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</pre>
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<!-- End of First Example -->
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<!-- Explanation of Numerical Range -->
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There are also other ways to specify the <i> numerical range </i>. For instance, if
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your numerical range is too big, you can simply write: <code> {1..100} </code>. This piece
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of code means every natural number between 1 and 100 (both included). <br>
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Ranges can also count backward like this: <code>{10..1}</code>.
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You can even increment the numerical value by step of two: <code> {0..10..2} </code>.
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This piece of code means every natural number between 0 and 10 with a step of two,
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0 2 4 6... 10.
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<!-- End of Explanation of Numerical Range -->
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