Options
-i makes an edit in-place. -i.bak will make an edit in-place, but create a backup file w/ suffix .bak
Quick reference
Replace text in all files in & under the current directory
find . -type f -exec sed -i 's/old/new/g' {} \;
-i makes an edit in-place. -i.bak will make an edit in-place, but create a backup file w/ suffix .bak
find . -type f -exec sed -i 's/old/new/g' {} \;