Change string char at index X

Question

I'm searched for a long time how to do a simple string manipulation in UNIX

I have this string:

theStr='...............' 

And I need to change the 5th char to A, How can it be done?

In C# it's done like this theStr[4] = 'A'; // Zero based index.

Answer 1

You can achieve this with sed, the stream line editor:

echo $theStr | sed s/./A/5

First you pipe the output of $theStr to sed, which replaces the fifth character with A.

Answer 2

a="............" b="${a:0:4}A${a:5}" echo ${b} 

Here is one really good tutorial on string manipulation.