bash bash中字符串的多次替换
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multiple substitutions on a string in bash
提问by Martin
I have a variable named inetwhich contains the following string:
我有一个名为的变量inet，其中包含以下字符串：
inet="inetnum: 10.19.153.120 - 10.19.153.127"
I would like to convert this string to notation below:
我想将此字符串转换为以下符号：
10.19.153.120 10.19.153.127
I could easily achieve this with sed 's/^inetnum: *//;s/^ -//', but I would prefer more compact/elegant solution and use bash. Nested parameter expansion does not work either:
我可以使用 轻松实现这一点sed 's/^inetnum: *//;s/^ -//'，但我更喜欢更紧凑/优雅的解决方案并使用 bash。嵌套参数扩展也不起作用：
$ echo ${${inet//inetnum: /}// - / }
bash: ${${inet//inetnum: /}// - / }: bad substitution
$
Any other suggestions? Or should I use sedthis time?
还有其他建议吗？还是我应该利用sed这个时间？
回答by Barmar
You can only do one substitution at a time, so you need to do it in two steps:
一次只能进行一次替换，因此需要分两步进行：
newinet=${inet/inetnum: /}
echo ${newinet/ - / }
回答by chepner
Use a regular expression in bashas well:
也使用正则表达式bash：
[[ $inet =~ ([0-9].*)\ -\ ([0-9].*)$ ]] && newinet=${BASH_REMATCH[@]:1:2}
The regular expression could probably be more robust, but should capture the two IP addresses in your example string. The two captures groups are found at index 1 and 2, respectively, of the array parameter BASH_REMATCHand assigned to the parameter newinet.
正则表达式可能更健壮，但应该捕获示例字符串中的两个 IP 地址。两个捕获组分别位于数组参数的索引 1 和 2 处，BASH_REMATCH并分配给参数newinet。
