Run arbitrary commands when files change.

# To call 'ls -la' when any file in the current directory changes:
watchexec -- <ls -la>

# To run 'make' when any JavaScript, CSS and HTML files in the current directory change:
watchexec --exts <js,css,html> make

# To run 'make' when any file in the 'lib' or 'src' subdirectories change:
watchexec --watch <lib> --watch <src> <make>

# To call/restart 'my_server' when any file in the current directory change, sending 'SIGKILL' to stop the child process:
watchexec --restart --signal <SIGKILL> <my_server>