entr

Run arbitrary commands when files change. More information: https://manned.org/entr.

• Rebuild with make if any file in any subdirectory changes:
  {{ag -l}} | entr {{make}}
• Rebuild and test with make if any .c source files in the current directory change:
  {{ls *.c}} | entr {{'make && make test'}}
• Send a SIGTERM to any previously spawned ruby subprocesses before executing ruby main.rb:
  {{ls *.rb}} | entr -r {{ruby main.rb}}
• Run a command with the changed file (/_) as an argument:
  {{ls *.sql}} | entr {{psql -f}} /_