37 lines
1,012 B
HTML
37 lines
1,012 B
HTML
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---
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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: variables, special, $, !
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author: Dario Rasic
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title: Script Special Variables
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---
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<!-- Intro -->
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<p>
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As previously said, there are certain characters that we can not use in the variable-naming process.
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<br>
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In this page we will see what actually are those characters, and what's their purpose.
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<br>
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<!-- list of commands-->
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<h4>$$</h4>
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To begin, we will see the simplest variable, which is the dollar sign ($). This command simply gives us the process ID number of the current shell.<br>
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<pre>
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echo $$
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11480
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</pre>
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<h4>$0</h4>
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This variable will simply give us the filename of the current script.
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<h4>$n</h4>
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This variable corresponds to the arguments with which a script was invoked. Here n is a positive number corresponding to the position of an argument.
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<h4>$#</h4>
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This variable gives us the number of arguments supplied to a script.
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<h4>$!</h4>
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This variable gives us the process number of the last background command.
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</p>
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