37 lines
728 B
Markdown
37 lines
728 B
Markdown
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# {
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> 多用途 shell 语法。
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> 更多信息：<https://www.gnu.org/software/bash/manual/bash.html>。
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- 隔离变量名：
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`echo ${{{HOME}work}}`
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- 使用大括号展开序列：
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`echo {{{1..3}}} {{{a..c}}}{{{dir1,dir2,dir3}}}`
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- 在返回文本之前检查 `variable` 是否已设置：
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`echo ${{{variable:+variable is set and contains $variable}}}`
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- 在 `variable` 未设置的情况下设置默认值：
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`echo ${{{variable:-default}}}`
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- 返回 `variable` 的字符长度：
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`echo ${{{#variable}}}`
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- 返回字符串切片：
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`echo ${{{variable:3:7}}}`
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- 递归展开一个 `variable`：
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`echo ${{{!variable}}}`
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- 将命令输出分组在一起：
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`{ {{command1; command2; ...}} } | {{another_command}}`
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