Shell programming: case 用法

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在 Shell programming中如何使用 case。

case 語法

case value in
    pattern1)
        command
        ...
        command
        ;;
    pattern2)
        command
        ...
        command
        ;;
    pattern3)
        command
        ...
        command
        ;;
    ...
esac

範例

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if [ "$#" -ne 1 ]
then
  echo "Usage: $0 [0-9]"
  exit 1
fi

case "$1" in
    0) echo zero;;
    1) echo one;;
    2) echo two;;
    3) echo three;;
    4) echo four;;
    5) echo five;;
    6) echo six;;
    7) echo seven;;
    8) echo eight;;
    9) echo nine;;
    *) echo "The input is not between 0 and 9."
esac

進階用法

  1. 多個情況匹配的時候，類似 or的功能
    pattern1 | pattern2

  2. 一個範圍匹配
    [0-9]