Bash脚本正则表达式

Question

我正在尝试匹配格式为4.6或2.8的字符串中的版本号.我将在我的.bashrc文件中的函数中最终使用以下内容来查找操作系统版本:

function test () {
    string="abc ABC12 123 3.4 def";
    echo `expr match "$string" '[0-9][.][0-9]'`
}

但是,这与字符串中的3.4不匹配.任何人都能指出我在正确的方向吗？

谢谢.

Answer 1

首先,您可以删除echo- expr在任何情况下将其结果打印到stdout.

其次,你的正则表达式需要括号(否则它打印匹配的字符数,而不是匹配本身),它需要从头开始.*.

expr match "$string" '.*\([0-9][.][0-9]\)'

从info expr页面:

STRING:REGEX'

 Perform pattern matching.  The arguments are converted to strings
 and the second is considered to be a (basic, a la GNU `grep')
 regular expression, with a `^' implicitly prepended.  The first
 argument is then matched against this regular expression.

 If the match succeeds and REGEX uses `\(' and `\)', the `:'
 expression returns the part of STRING that matched the
 subexpression; otherwise, it returns the number of characters
 matched.

Answer 2

根据您的bash版本,不需要调用expr:

$ [[ "abc ABC12 123 3.4 def" =~ [0-9][.][0-9] ]] && echo ${BASH_REMATCH[0]}
3.4