This chapter documents the coding style used in live systems.
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Don't use syntax or semantics that are unique to the Bash shell. For example, the use of array constructs.
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Only use the POSIX subset - for example, use $(foo) over `foo`.
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You can check your scripts with 'sh -n' and 'checkbashisms'.
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Make sure all shell code runs with 'set -e'.
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Always use tabs over spaces.
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Generally, lines are 80 chars at maximum.
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Use the "Linux style" of line breaks:
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The same holds for functions:
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Variables are always in capital letters.
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Variables used in live-build always start with LB_ prefix.
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Internal temporary variables in live-build should start with the _LB_ prefix.
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Local variables start with live-build __LB_ prefix.
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Variables in connection to a boot parameter in live-config start with LIVE_.
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All other variables in live-config start with _ prefix.
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Use braces around variables; e.g. write ${FOO} instead of $FOO.
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Always protect variables with quotes to respect potential whitespaces: write "${FOO}" not ${FOO}.
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For consistency reasons, always use quotes when assigning values to variables:
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If multiple variables are used, quote the full expression:
if [ -f "${FOO}"/foo/"${BAR}"/bar ]
then
foobar
fi
if [ -f "${FOO}/foo/${BAR}/bar" ]
then
foobar
fi
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Use "|" (without the surround quotes) as a separator in calls to sed, e.g. "sed -e 's|foo|bar|'" (without "").
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Don't use the test command for comparisons or tests, use "[" "]" (without ""); e.g. "if [ -x /bin/foo ]; ..." and not "if test -x /bin/foo; ...".
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Use case wherever possible over test, as it's easier to read and faster in execution.
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Use capitalized names for functions to limit messing with the users environment.
