9d865abee1
* [: use posix-compliant example for equals comparison the previous example worked fine for bash, but some other shells (zsh, in my case) will not work when using "==" for comparison. the posix spec only requires "=", so I think it makes a little more sense to use that in the example. * test: use posix-compliant example for equals comparison the previous example worked fine for bash, but some other shells (zsh, in my case) will not work when using "==" for comparison. the posix spec only requires "=", so I think it makes a little more sense to use that in the example.
34 lines
853 B
Markdown
34 lines
853 B
Markdown
# [
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> 检查文件类型，比较数值。
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> 如果条件计算结果为真返回 0，如果计算结果为假返回 1。
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> 更多信息：<https://www.gnu.org/software/bash/manual/bash.html#index-test>.
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- 测试一个给定的变量是否等于/不等于指定的字符串：
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`[ "${{变量}}" {{=|!=}} "{{字符串}}" ]`
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- 测试一个给定的变量是否等于/不等于/大于/小于/大于等于/小于等于指定的数字：
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`[ "${{变量}}" -{{eq|ne|gt|lt|ge|le}} {{数字}} ]`
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- 测试指定的变量的值是否非空：
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`[ -n "${{变量}}" ]`
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- 测试指定变量的值是否为空：
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`[ -z "${{变量}}" ]`
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- 测试指定文件是否存在：
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`[ -f {{路径/到/文件}} ]`
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- 测试指定目录是否存在：
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`[ -d {{路径/到/目录}} ]`
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- 测试指定文件或目录是否存在：
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`[ -e {{路径/到/文件或目录}} ]`
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