Linux Shell 脚本：如何剪切字符串的一部分

Shell script : How to cut part of a string

提问by deimus

I have following string

我有以下字符串

a   a3 eGalax Inc. USB TouchController          id=9    [slave  pointer  (2)]
a   a3 eGalax Inc. USB TouchController          id=10   [slave  pointer  (2)]

and would like to get the list of id ? How this can be done using sed or something else ?

并想获得 id 的列表？如何使用 sed 或其他方法完成此操作？

采纳答案by Manoj Govindan

I pasted the contents of your example into a file named so.txt.

我将您示例的内容粘贴到名为so.txt.

$ cat so.txt | awk '{ print  }' | cut -f2 -d"="
9
10

Explanation:

解释：

1. cat so.txtwill print the contents of the file to stdout.
2. awk '{ print $7 }'will print the seventh column, i.e. the one containing id=n
3. cut -f2 -d"="will cut the output of step #2 using =as the delimiter and get the second column (-f2)

1. cat so.txt将文件的内容打印到stdout.
2. awk '{ print $7 }'将打印第七列，即包含 id=n
3. cut -f2 -d"="将使用=作为分隔符的步骤 #2 的输出并获得第二列 ( -f2)

If you'd rather get id=also, then:

如果你id=也想得到，那么：

$ cat so.txt | awk '{ print  }' 
id=9
id=10

回答by bluebrother

Use a regular expression to catch the id number and replace the whole line with the number. Something like this should do it (match everything up to "id=", then match any number of digits, then match the rest of the line):

使用正则表达式来捕捉 id 号并用数字替换整行。应该这样做（匹配所有内容到“id=”，然后匹配任意数量的数字，然后匹配该行的其余部分）：

sed -e 's/.*id=\([0-9]\+\).*//g'

Do this for every line and you get the list of ids.

对每一行执行此操作，您将获得 id 列表。

回答by sid_com

A perl-solution:

一个 perl 解决方案：

perl -nE 'say  if /id=(\d+)/' filename

回答by Paused until further notice.

You can have awkdo it all without using cut:

您可以在awk不使用的情况下完成所有操作cut：

awk '{print substr(,index(,"=")+1)}' inputfile

You could use split()instead of substr(index()).

您可以使用split()代替substr(index()).

回答by ghostdog74

$ ruby -ne 'puts $_.scan(/id=(\d+)/)' file
9
10

回答by frayser

Assuming input of

假设输入

{Anything}id={ID}{space}{Anything} 
{Anything}id={ID}{space}{Anything}

--

——

#! /bin/sh
while read s; do
   rhs=${s##*id=}
   id=${rhs%% *}
   echo $id # Do what you will with $id here
done <so.txt 

Or if it's always the 7th field

或者如果它总是第 7 个字段

#! /bin/sh
while read f1 f2 f3 f4 f5 f6 f7 rest
do
echo ${f7##id=}
done <so.txt

See Also

也可以看看

Shell Parameter Expansion

外壳参数扩展