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How to extract string between two specified characters and end of line?


 
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# 8  
Old 03-03-2020
The below code is throwing error too

Code:
#!/bin/bash
while read line
do
key= $(sed 's/\(.*\)\=.*/\1/' $line)
value=$(sed 's/.*\=//g' $line)
sed "s/$key/$value/g" test.txt
done <  bbb.txt

Moderator's Comments:
Mod Comment
Please use code tags when posting data and code samples!

Last edited by vgersh99; 03-03-2020 at 04:28 PM.. Reason: code tags, please!
# 9  
Old 03-03-2020
Hi
Code:
key= $(sed 's/\(.*\)\=.*/\1/' $line)

There should be no space after the equal sign
Code:
key=$(sed 's/\(.*\)\=.*/\1/' $line)

put error messages in the post too
# 10  
Old 03-03-2020
Furthermore, sed gets the $line as a filename.
If it should get it as input then do
Code:
echo "$line" | sed ...

Some shells (bash, zsh) take as well
Code:
sed ... <<< "$line"

This User Gave Thanks to MadeInGermany For This Post:
# 11  
Old 03-04-2020
extract string between two specified characters and end of line

You can leave the $start or $end arguments empty and it will use the start or end of the string.

Code:
echo get_string_between("Hello my name is bob", "my", ""); //output: " name is bob"

private function get_string_between($string, $start, $end){ // Get
    if($start != ''){ //If $start is empty, use start of the string
        $string = ' ' . $string;
        $ini = strpos($string, $start);
        if ($ini == 0) return '';
        $ini += strlen($start);
    }
    else{
        $ini = 0;
    }

    if ($end == '') { //If $end is blank, use end of string
        return substr($string, $ini);
    }
    else{
        $len = strpos($string, $end, $ini) - $ini; //Work out length of string
        return substr($string, $ini, $len);
    }
}


Last edited by vgersh99; 03-04-2020 at 11:29 AM.. Reason: fix code tags
# 12  
Old 03-04-2020
Thanks for the suggestion. that worked. But now the last part of replacing it in a different file is not working. I tried the below two codes.

Code:
#!/bin/bash
while read line
do
key= echo "$line" | sed 's/\(.*\)\=.*/\1/' 
value= echo "$line" | sed 's/.*\=//'
sed 's/$key/$value/g' test.txt
done < bbb.tx

Code:
#!/bin/bash
input=/home/wip4599/test.txt
while read line
do
key= echo "$line" | sed 's/\(.*\)\=.*/\1/' 
value= echo "$line" | sed 's/.*\=//'
sed 's/$key/$value/g' $input
done < bbb.txt

--- Post updated at 08:04 PM ---

@MadeInGermany

--- Post updated at 08:42 PM ---

used the below format and it worked

Code:
key=$(echo "$line" | sed 's/\(.*\)\=.*/\1/')


Last edited by Scrutinizer; 03-04-2020 at 03:54 PM.. Reason: code tags
# 13  
Old 03-04-2020
Yes that is the correct format.
And it should be sed "s/$key/$value/g" with normal (double-)quotes, so the shell can expand $key and $value.

A more efficient way is to let the read command spllit into fields and directly assign them to distinct variables.
We can set the "input field separator" IFS to = (by default it is whitespace). By prefixing IFS="=" we set this environment variable only for the following read command.
Code:
input=/home/wip4599/test.txt
while IFS="=" read key value
do
  sed "s/$key/$value/g" $input
done < bbb.txt

# 14  
Old 03-05-2020
both the codes are replacing all the matching pattern. If I have $$Date and $$Date_1 it is replacing like 20200305 and 20200305_1 but I have different values for $$Date_1. How to skip that. if I try this echo statement its working but not when im using variables key and value.

echo $(sed -e 's/^$$Date$/20200305/g' test.txt)

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