如何在一个文件的子串位置上使用info从另一个文件中提取子串（loop，bash）

I'm trying quite hard to write a script that "loopingly" extracts substrings from one file, while getting the information on where to cut from another file. I'm working in bash on MobaXterm. I have the file cut_positions.txt, which is tab delimited and shows name, start point, end point, length, comment:I'm trying quite hard to write a script that "l