1. if
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if [ test ]; then
    xxxx
elif [ test ]; then
    xxxx
else
    xxxx
fi
  1. for
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for it in list; do
    xxxx $it
done
  1. while
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while [ test ]; do
    xxxx
done
  1. case
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case $var in
    "a")
        xxxx;;
    "b")
        xxxx;;
    *)  #default
        xxxx;;
esac