BASH：如何提取子由特定的文本包围 [英] BASH: How to extract substring that is surrounded by specific text

问题描述

我试图提取遵循特定模式的文件名编号：

I am trying to extract numbers from file names that follow a specific pattern:

file-8923489_something.txt
another_file-8923489_something.txt
some-other_file-8923489_something.txt

欲提取是文本文件级和_something，将与上述3的文件名的工作之间的数目。

I want to extract the number that is between text "file-" and "_something" that will work with the above 3 file names.

什么是去最好的方法？

是否有可能做到这一点只能通过运营商，如##和%%？如何是这样的：

Is it possible to do this using operators only, such as ## and %%? How about something like:

filename=file-8923489_something.txt
file=${${filename##*file}%%_something}}

但是，如我所料没有工作。

However, it didn't work as I expected.

推荐答案

使用pre BASH正则表达式：

Using pre BASH regex:

x="some-other_file-8923489_something.txt"
[[ "$x" =~ file-([0-9]*)_something ]] && echo ${BASH_REMATCH[1]}
8923489

或本的grep -P 也将工作：

grep -oP "file-\K\d+(?=_something)" file
8923489
8923489
8923489

或使用awk的：

awk -F 'file-|_something' '{print $2}' file
8923489
8923489
8923489

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