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| | .SS The \'.include\' Directive |
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| | At any point in a configuration file, you can "include" another configuration file |
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| | like this: |
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| | .nf |
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| | .include filename |
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| | .fi |
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| | In fact, you can use all the variable substitution and string concatenation features we've |
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| | already discussed to do this symbolically: |
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| | .nf |
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| | Base = MyConfig |
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| | Ver = 1.01 |
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| | .include [Base]-[Ver].cfg |
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| | .fi |
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| | The whitespace after the \'.include\' directive is mandatory to separate it from |
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| | the file name. You can have as many \'.include\' statements in your configuration file |
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| | as you wish, and they may appear anywhere. The only restriction is that they must |
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| | appear on a line by themselves (with an optional comment). |
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| | Why bother? There are several reasons: |
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| | .IP \(bu 4 |
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| | This makes it easy to break up large, complex configurations into simpler (smaller) |
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| | pieces. |
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| | .IP \(bu 4 |
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| | This makes is easy to "factor" common configuration information into separate |
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| | files which can then be used by different programs as needed. |
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| | .IP \(bu 4 |
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| | But the most common use for \'.include\' is to load a "standard" configuration for |
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| | your program. Recall that the last assignment of a variable's value "wins". |
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| | Suppose you want all the standard settings for a program, but you just want to |
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| | change one or two options. Instead of requiring each user to have the whole |
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| | set of standard settings in their own configuration file, the system administrator |
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| | can make them available as a common configuration. Each user \'.include\'s |
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| | that file and then overrides any options they like: |
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| | .nf |
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| | # Get the standard options |
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| | .include /usr/local/etc/MyAppStandardConfig.cfg |
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| | # Override the ones you like |
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| | ScreenColor = Blue |
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| | Currency = Euros |
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| | .fi |
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| | This makes maintenance of complex configuration files |
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| | .B much |
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| | simpler. There is only one master copy of the configuration that needs to be |
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| | edited when system-wide changes are required. |
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| | .P |
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| | One last thing needs to be noted here. \*(TC does not detect so-called "circular" |
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| | inclusions. If file \'a\' \'.include\'s file \'b\' and file \'b\' \'.include\'s file \'a\', you will |
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| | have an infinite loop of inclusion, which, uh, is a Bad Thing... |
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| | .SS Conditional Directives |
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| | .SS The \'.literal\. Directive |
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tundra
authored
on 16 Apr 2004