Pure shell implementation of text replacement

Blog Background

Do not rely on tr and do not rely on sed to achieve text replacement using pure shell

Detailed operation

Note: The test takes effect under bash version 5.1.16, but it doesn't seem to take effect under version 5.0

echo hello | while read -r str; do echo "${str//l/n}"; done

echo hello | (read -r str; echo "${str//l/n}")