How to change the owner/group of a file or directory recursively.
sudo chown -R newusername foldername
To change the group:
sudo chgrp -R newgroupname foldername
Read a text file in bash line by line with while. It will read till the end of line. You can modify the end of line setting a new value to EOF variable.
while read line; do echo "${line}"; done < <(cat file.lst)