Root/docs/config.tex

1\subsubsection{Structure of the configuration files}
2
3The config files are divided into sections and options/values.
4
5Every section has a type, but does not necessarily have a name.
6Every option has a name and a value and is assigned to the section
7it was written under.
8
9Syntax:
10
11\begin{Verbatim}
12config <type> ["<name>"] # Section
13    option <name> "<value>" # Option
14\end{Verbatim}
15
16Every parameter needs to be a single string and is formatted exactly
17like a parameter for a shell function. The same rules for Quoting and
18special characters also apply, as it is parsed by the shell.
19
20\subsubsection{Parsing configuration files in custom scripts}
21
22To be able to load configuration files, you need to include the common
23functions with:
24
25\begin{Verbatim}
26. /lib/functions.sh
27\end{Verbatim}
28
29Then you can use \texttt{config\_load \textit{<name>}} to load config files. The function
30first checks for \textit{<name>} as absolute filename and falls back to loading
31it from \texttt{/etc/config} (which is the most common way of using it).
32
33If you want to use special callbacks for sections and/or options, you
34need to define the following shell functions before running \texttt{config\_load}
35(after including \texttt{/lib/functions.sh}):
36
37\begin{Verbatim}
38config_cb() {
39    local type="$1"
40    local name="$2"
41    # commands to be run for every section
42}
43
44option_cb() {
45    # commands to be run for every option
46}
47\end{Verbatim}
48
49You can also alter \texttt{option\_cb} from \texttt{config\_cb} based on the section type.
50This allows you to process every single config section based on its type
51individually.
52
53\texttt{config\_cb} is run every time a new section starts (before options are being
54processed). You can access the last section through the \texttt{CONFIG\_SECTION}
55variable. Also an extra call to \texttt{config\_cb} (without a new section) is generated
56after \texttt{config\_load} is done.
57That allows you to process sections both before and after all options were
58processed.
59
60Another way of iterating on config sections is using the \texttt{config\_foreach} command.
61
62Syntax:
63\begin{Verbatim}
64config_foreach <function name> [<sectiontype>] [<arguments...>]
65\end{Verbatim}
66
67This command will run the supplied function for every single config section in the currently
68loaded config. The section name will be passed to the function as argument 1.
69If the section type is added to the command line, the function will only be called for
70sections of the given type.
71
72
73You can access already processed options with the \texttt{config\_get} command
74Syntax:
75
76\begin{Verbatim}
77# print the value of the option
78config_get <section> <option>
79
80# store the value inside the variable
81config_get <variable> <section> <option>
82\end{Verbatim}
83
84In busybox ash the three-option \texttt{config\_get} is faster, because it does not
85result in an extra fork, so it is the preferred way.
86
87Additionally you can also modify or add options to sections by using the
88\texttt{config\_set} command.
89
90Syntax:
91
92\begin{Verbatim}
93config_set <section> <option> <value>
94\end{Verbatim}
95
96If a config section is unnamed, an automatically generated name will
97be assigned internally, e.g. \texttt{cfg1}, \texttt{cfg2}, ...
98
99While it is possible, using unnamed sections through these autogenerated names is
100strongly discouraged. Use callbacks or \texttt{config\_foreach} instead.
101
102

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