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A Practical Guide to Ubuntu Linux®, Fourth Edition by Mark G. Sobell

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Image Variables

Variables, introduced on page 358, are shell parameters denoted by a name. Variables can have zero or more attributes (page 362; e.g., export, readonly). You, or a shell program, can create and delete variables, and can assign values and attributes to variables. This section adds to the previous coverage with a discussion of the shell variables, environment variables, inheritance, expanding null and unset variables, array variables, and variables in functions.

Shell Variables

By default, when you create a variable it is available only in the shell you created it in; it is not available in subshells. This type of variable is called ...

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