How to find and replace every occurrence of
in every file of name "access.html" in a particular folder
shopt -s globstar sed -i.bak 's/httpaccess/&abc/g' **/access.html
**to match your filename, recursively.
sed -ito perform an in-place substitution.
This will create backup files with a suffix
.bak. To unset the shell option, use
shopt -u globstar afterwards.