bash find replace in file code example

Example 1: how to find and replace a string in a file using shell script

# replaces ALL(g i.e. global) ouccurences of "original_string" with "new_string", 
# in the file file_name.ext_name
sed -i 's/original_string/new_string/g' file_name.ext_name

Example 2: bash find and replace all files with specifc name with another file

find . -name "boom.txt" -exec cp ~/replace.txt {} \;