c0a6a75fce
git-svn-id: svn+ssh://atelier.inf.usi.ch/home/bevilj/group-1@280 a672b425-5310-4d7a-af5c-997e18724b81
36 lines
1019 B
HTML
36 lines
1019 B
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: variables special $ !
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author: Dario Rasic
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title: Script Special Variables
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previous-page: pages/scripts/1-variables.html
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next-page: pages/scripts/3-parameter_expansion.html
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---
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<!-- Intro -->
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There are certain strings that we can't use in the variable-naming process.<br>
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In this page we will see what those strings are, and what their purpose is.<br>
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<h4>$$</h4>
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To begin, we look at the simplest variable, which is the dollar sign ($).
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This command simply gives us the process ID of the current shell.<br>
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<pre>
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echo $$
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11480
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</pre>
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<h4>$0</h4>
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This variable simply gives us the filename of the current script.
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<h4>$n</h4>
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This variable corresponds to the arguments with which a script was invoked.
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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 ID of the last background command.
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