SHELL命令--grep

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本文详细解析了正则表达式的基础概念，包括、B、w、W、s、S等特殊字符的含义与使用场景，通过示例说明了如何在grep命令中应用这些特殊字符进行精确匹配。

注意事项

\b、\B、‘\<、\w、\W、\s、\S在单引号和双引号中无差异,grep 'cur_path\s*=' install.sh与grep "cur_path\s=" install.sh作用相同；

The ‘\’ character, when followed by certain ordinary characters, takes a special meaning:
‘\b’ ： Match the empty string at the edge of a word.
‘\B’ ： Match the empty string provided it’s not at the edge of a word.
‘\<’ ： Match the empty string at the beginning of word.
‘\>’ ： Match the empty string at the end of word.
‘\w’ ： Match word constituent, it is a synonym for ‘[_[:alnum:]]’.
‘\W’ ： Match non-word constituent, it is a synonym for ‘[^_[:alnum:]]’.
‘\s’ ：  Match whitespace, it is a synonym for ‘[[:space:]]’.
‘\S’ ： Match non-whitespace, it is a synonym for ‘[^[:space:]]’.
 For example, ‘\brat\b’ matches the separate word ‘rat’, ‘\Brat\B’ matches ‘crate’ but not ‘furry rat’.

示例-1：

if grep -q "BAD\!\|^FATAL:" echo_client.log; then
        echo "************** Found bug! ***************"
        echo "Check echo_client.log for client logs"
        exit 1
fi