如何使用sed从字符串中的特定点提取文本？

Question

I want to break single string into two different strings using sed .

For eg:

STRING := folder1_test.abc_xxx

STRING1 := folder1_test

STRING2 := abc_xxx

or 

STRING := folderB_test folderA_test.yyyy_xx 

STRING1 := folderB_test folderA_test

STRING2 := yyyy_xx

So whatever is before dot(.) I want in first string and after dot(.) I want that thing in second string.

Specifically with sed command only. As I am using in makefile implementation.

Answer 1

One command line:

With tr cmd:

echo 'folderB_test folderA_test.yyyy_xx' | tr "." "\n"
# gives folderB_test folderA_test
#       yyyy_xx

With cut (set delimiter to . and display field 1 (-f1)):

echo 'folderB_test folderA_test.yyyy_xx' | cut -d. -f1
# gives folderB_test folderA_test

With cut (set delimiter to . and display field2 (-f2)):

echo 'folderB_test folderA_test.yyyy_xx' | cut -d. -f2
# gives yyyy_xx

Store result in an array and read it:

#!/bin/bash

IN="bla@some.com;john@home.com"

#With tr cmd:
arr=$(echo $IN | tr ";" "\n")

#With sed cmd:
arr=$(echo $IN | sed 's/;/\'$'\n/g')

for x in $arr
do
    echo "$x"
done

Gives:

bla@some.com
john@home.com

Answer 2

From your post I understand that you need this in a Makefile (and the syntax is confirming this). In that case this is what you need: https://stackoverflow.com/a/8540718/3464942

For example:
STRING1 := $(firstword $(subst ., ,$(STRING)))
STRING2 := $(or $(word 2,$(subst ., ,$(STRING))),$(value 2))

Answer 3

Using parameter expansion

$ str='folder1_test.abc_xxx'
$ echo "${str%.*}"
folder1_test
$ echo "${str#*.}"
abc_xxx

$ str='folderB_test folderA_test.yyyy_xx'
$ echo "${str%.*}"
folderB_test folderA_test
$ echo "${str#*.}"
yyyy_xx

replace echo with variable assignment as per requirement

$ string='folderB_test folderA_test.yyyy_xx'
$ string1="${string%.*}"
$ echo "$string1"
folderB_test folderA_test
$ string2="${string#*.}"
$ echo "$string2"
yyyy_xx

Note: It is preferable to use lowercase for user defined variables

Answer 4

I think it will answer your question.

sed 's/\\(^\\(.*\\)\\.\\(.*\\)$\\)/STRING : \\1\\nSTRING 1: \\2\\nSTRING 2: \\3/g'

Ex:

sed 's/(^(. ).(. )$)/STRING : \\1\\nSTRING 1: \\2\\nSTRING 2: \\3/g'

folderB_test folderA_test.yyyy_xx //input

STRING : folderB_test folderA_test.yyyy_xx

STRING 1: folderB_test folderA_test

STRING 2: yyyy_xx