Entr and many other similar alternatives do not satisfy my needs. The main fault is that they take list of files instead of root directory and possibly include/exclude patterns. So when I create or rename files, these tools either don't register new files, or they just fail on missing files.
I'm rather reusing existing stuff but seeing how every scriptable filesystem watcher misses the point, I'm inclined to write my own inotifywait/inotifywatch wrapper.
That's literally in the article; `entr -d`. The manpage also has an entry. http://eradman.com/entrproject/entr.1.html#d
Terminal 1:
mkdir /tmp/project
cd /tmp/project
touch file{1,2}
ls | entr -d echo "a change"
rm file2
entr: cannot open 'file2': No child processes
> Track the directories of regular files provided as input and exit if a new file is added. This option also enables directories to be specified explicitly. Files with names beginning with ‘.’ are ignored.
So first, it doesn't track NEW directories, and second, it exits if new file is added. Exactly how is this useful?
EDIT: All I want from filesystem watcher is to track files by pattern and just re-run the command, however complex that may be to implement via OS interfaces. When I'm working on a Python project that has packages (directories), I may also refactor (rename files), and this simplistic behavior does not catch that.
> All I want from filesystem watcher is to track files by pattern and just re-run the command, however complex that may be to implement via OS interfaces.
I've had good luck with modd: https://github.com/cortesi/modd/
I just tested exactly what you described, did not see any errors, and it ran my commands exactly the way I wanted.
I would also like to extol virtues of its sister project devd[0] from same author which makes web development palatable to me. It's a little websocker server that injects a tiny script into HTML to reload the page in browser once modd detects file change, rebuilds front-end and sends devd a SIGHUP.