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A Practical Guide to Linux® Commands, Editors, and Shell Programming, Third Edition by Mark G. Sobell

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Variables

Like human languages, Perl distinguishes between singular and plural data. Strings and numbers are singular; lists of strings or numbers are plural. Perl provides three types of variables: scalar (singular), array (plural), and hash (plural; also called associative arrays). Perl identifies each type of variable by a special character preceding its name. The name of a scalar variable begins with a dollar sign ($), an array variable begins with an at sign (@), and a hash variable begins with a percent sign (%). As opposed to the way the shell identifies variables, Perl requires the leading character to appear each time you reference a variable, including when you assign a value to the variable:

$ name="Zach" ; echo "$name"                   (bash) ...

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