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102 lines
3.3 KiB
TeX
102 lines
3.3 KiB
TeX
\subsubsection{Structure of the configuration files}
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The config files are divided into sections and options/values.
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Every section has a type, but does not necessarily have a name.
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Every option has a name and a value and is assigned to the section
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it was written under.
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Syntax:
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\begin{Verbatim}
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config <type> ["<name>"] # Section
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option <name> "<value>" # Option
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\end{Verbatim}
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Every parameter needs to be a single string and is formatted exactly
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like a parameter for a shell function. The same rules for Quoting and
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special characters also apply, as it is parsed by the shell.
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\subsubsection{Parsing configuration files in custom scripts}
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To be able to load configuration files, you need to include the common
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functions with:
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\begin{Verbatim}
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. /lib/functions.sh
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\end{Verbatim}
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Then you can use \texttt{config\_load \textit{<name>}} to load config files. The function
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first checks for \textit{<name>} as absolute filename and falls back to loading
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it from \texttt{/etc/config} (which is the most common way of using it).
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If you want to use special callbacks for sections and/or options, you
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need to define the following shell functions before running \texttt{config\_load}
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(after including \texttt{/lib/functions.sh}):
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\begin{Verbatim}
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config_cb() {
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local type="$1"
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local name="$2"
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# commands to be run for every section
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}
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option_cb() {
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# commands to be run for every option
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}
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\end{Verbatim}
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You can also alter \texttt{option\_cb} from \texttt{config\_cb} based on the section type.
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This allows you to process every single config section based on its type
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individually.
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\texttt{config\_cb} is run every time a new section starts (before options are being
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processed). You can access the last section through the \texttt{CONFIG\_SECTION}
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variable. Also an extra call to \texttt{config\_cb} (without a new section) is generated
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after \texttt{config\_load} is done.
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That allows you to process sections both before and after all options were
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processed.
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Another way of iterating on config sections is using the \texttt{config\_foreach} command.
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Syntax:
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\begin{Verbatim}
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config_foreach <function name> [<sectiontype>] [<arguments...>]
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\end{Verbatim}
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This command will run the supplied function for every single config section in the currently
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loaded config. The section name will be passed to the function as argument 1.
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If the section type is added to the command line, the function will only be called for
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sections of the given type.
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You can access already processed options with the \texttt{config\_get} command
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Syntax:
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\begin{Verbatim}
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# print the value of the option
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config_get <section> <option>
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# store the value inside the variable
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config_get <variable> <section> <option>
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\end{Verbatim}
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In busybox ash the three-option \texttt{config\_get} is faster, because it does not
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result in an extra fork, so it is the preferred way.
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Additionally you can also modify or add options to sections by using the
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\texttt{config\_set} command.
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Syntax:
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\begin{Verbatim}
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config_set <section> <option> <value>
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\end{Verbatim}
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If a config section is unnamed, an automatically generated name will
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be assigned internally, e.g. \texttt{cfg1}, \texttt{cfg2}, ...
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While it is possible, using unnamed sections through these autogenerated names is
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strongly discouraged. Use callbacks or \texttt{config\_foreach} instead.
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