Replace substring of a line with a given string

Question

I am trying to replace name with a different name, which works but when I have "[]" it doesn't work.

#!/bin/bash
firstString="I love [Candy] Store"
firstChange="[Candy] Store"
secondString="Chocolate Store"
echo "${firstString//$firstChange/$secondString}"

I am expecting:

"I love Chocolate Store".

Working example:

#!/bin/bash
firstString="I love Candy Store"
firstChange="Candy Store"
secondString="Chocolate Store"
echo "${firstString//$firstChange/$secondString}"

Output:

I love Chocolate Store.

I am trying to make it work for both the cases.

Could someone please help me?

Thanks

Andrew McGuinness · Accepted Answer · 2019-02-01T16:10:19.160

0

Well, this works:

#!/bin/bash
firstString="I love [Candy] Store"
firstChange="\[Candy\] Store"
secondString="Chocolate Store"
echo "${firstString//$firstChange/$secondString}"

It may not help you much; if your "change" string is input from somewhere you can't count on it being properly escaped.

The problem is that the bash expansion is treating the firstChange value as a pattern not a regular string.

Per this answer https://stackoverflow.com/a/2856010/200136 , printf "%q" is the solution:

#!/bin/bash
firstString="I love [Candy] Store"
firstChange="[Candy] Store"
printf -v quoteChange "%q\n" $firstChange
safeChange=$(echo $quoteChange)
secondString="Chocolate Store"
echo "${firstString//$safeChange/$secondString}"

edited Feb 01 '19 at 16:10

answered Feb 01 '19 at 16:02

Andrew McGuinness

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18

umm.. [Candy] Store is passed as a string, so I don't think I can modify it as you mentioned above – user10913544 Feb 01 '19 at 16:04
Yes, that's what I meant by "may not help you much". Edited to include a solution that might be more general – Andrew McGuinness Feb 01 '19 at 16:11
I was able to solve it by doing: echo "${firstString//"$firstChange"/$secondString}" – user10913544 Feb 01 '19 at 16:14
Thank you so much for your help, I got the idea from your solution :) – user10913544 Feb 01 '19 at 16:15

Replace substring of a line with a given string

1 Answers1