用于行首和行尾的 Grep? [英] Grep for beginning and end of line?

问题描述

我有一个文件，我想在其中对以 -rwx 或 drwx 开头并以任意数字结尾的行进行 grep.

I have a file where I want to grep for lines that start with either -rwx or drwx AND end in any number.

我有这个，但不太正确.有什么想法吗?

I've got this, but it isnt quite right. Any ideas?

grep [^.rwx]*[0-9] usrLog.txt

推荐答案

棘手的部分是包含破折号作为字符类中有效字符之一的正则表达式.对于(正常)字符类，破折号必须紧跟在开始之后，对于否定字符类，必须紧跟在脱字符之后.如果您也需要一个右方括号，那么您需要右方括号后跟破折号.幸运的是，您只需要破折号，因此选择了符号.

The tricky part is a regex that includes a dash as one of the valid characters in a character class. The dash has to come immediately after the start for a (normal) character class and immediately after the caret for a negated character class. If you need a close square bracket too, then you need the close square bracket followed by the dash. Mercifully, you only need dash, hence the notation chosen.

grep '^[-d]rwx.*[0-9]$' "$@"

参见:正则表达式和grep 了解 POSIX 标准的详细信息.

See: Regular Expressions and grep for POSIX-standard details.

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