Entr 2.2 Formula

entr is a portable utility to run a command when files change

From the man page:
EXAMPLES
     Recompile when source files change

           $ find. -name '*.c' | entr make

     Launch and auto-reload a node.js server

           $ echo *.js | entr -r node index.js

     Convert individual Markdown files to HTML if they're modified

           $ ls *.md | entr +notify &
           $ while read F; do
           > markdown2html $F
           > done < notify