sed command replace string code example

Example 1: ubuntu command line replace word in files

sed -i 's/original/new/g' file.txt

Example 2: sed replace in file

sed -i 's/foo/bar/g' hello.txt

Example 3: sed replace with variable

Just concatenate var '"$var"' to replace values string in sed command:
$ sed -i 's/string_to_replace/'"$var"'/g' file_to_replace.txt