Sed

https://opensource.com/article/20/12/sed

grep -rl oldtext . | xargs sed -i 's/oldtext/newtext/g'

find . -type f -name "*.txt" -exec sed -i 's/old_text/new_text/g' {} +

find . -type f -name "*.txt" -exec sed -i 's/old_text/new_text/g' {} +

find . -type f -name "*.txt" -print0 | xargs -0 sed -i 's/old_text/new_text/g'v

Linux

grep -rlZ --exclude-dir='.git' 'oldtext' . | xargs -0 sed -i 's/oldtext/newtext/g'

Macos/freebsd

grep -rl --null --exclude-dir='.git' 'oldtext' . | xargs -0 sed -i 's/oldtext/newtext/g'