I’m trying to take a substring of a string read from a file and put it in a variable. The string will look something like this:

I have a tab-delimited file that contains 4 columns

This is my file:

I have a file that used to contain two CSV columns but has had its commas removed so that each line is one full “record”. I need to separate these into two records again by adding a comma, but the lines are between 20 to 21 characters and need to be processed accordingly – if the line is 20 characters the comma needs to be added at the 16th position, and if the line is 21 characters the comma needs to be added at the 17th position. If I’ve done my maths right this would result in a second column that has 5 characters on all lines.

find proper regular files and pass to sed to perform replacement of string

I have code in bash scripting to extract some values in variables.
Text is:

I have a configuration file where I need to append the version in ascending order. For this I have written a shell script. The value is getting appended, but the position is not correct.