There is inotifywait which seems to do the job, The Wiki
this post was submitted on 25 Aug 2025
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After some suggestions to check out inotifywait I ended up with a solution that works for me as desired.
inotifywait --event modify,create ./targetfolder/; echo "new change, that I am interested in, occurred in targetfolder";
It turned out I was interested in both file modification and file creation events.
Maybe inotify or one of those "watcher" (not "watch") tools available, but I don't remember which one to use.
The simplest solution is entr, I use it a lot for development - https://www.linuxbash.sh/post/entr-rerun-commands-when-files-change
What is the end goal?
a hobby project: generate a rss feed based on recent file changes in a directory. But I thought this can also have many applications …
- auto formatting code files on change
- automatic backups of a certain folder: run rsync on change in folder.
Are you familiar with CI/CD pipelines? You could use Git along with a service like Woodpecker CI or Gitlab Runners.
Can continuously loop over the file, examine the md5 hash for changes.
Run the script if it has changed.
https://stackoverflow.com/questions/6475252/bash-script-watch-folder-execute-command
daemon() {
chsum1=""
while [[ true ]]
do
chsum2=`find src/ -type f -exec md5 {} \;`
if [[ $chsum1 != $chsum2 ]] ; then
if [ -n "$chsum1" ]; then
compile
fi
chsum1=$chsum2
fi
sleep 2
done
}
Oh god please don’t do this. Constantly reading the file is just stressing your IO for no reason.
Please inotify instead:
The fuck…
Even if you wanted to implement a solution like this, which you shouldn't, why on earth monitor the MD5 sum instead of just the mtime of the file???? Like, doing a checksum is the least efficient method of checking this possible.
Like, you could do a simple while loop with a find myfile.txt +mmin 1; sleep 30 in it. Adjust numbers to your desired tolerance.
Again, don't do that. But if you must, definitely don't do an md5sum for godssake.
I really like this, replace compile with whatever command you desire I guess.
This is a terrible solution. You will stress your IO for no reason.
On the upside, you do not need to install the inotifywait package. md5sum already installed on my system haha
If you are a big fan of wasting disk performance, CPU cycles, and ultimately power.
It isn't a terrible solution if you are checking infrequently just as ever 30 minutes.
why is that a plus
I do not need to install anything/can work on bare install without internet connection?
ah, fair.
You should be able to tie into the kernel with some C programming if you want to go extra small.
Block execution not entirely. You could chmod it as non-x and use inotifywatch to flip it back.
Edit: I misunderstood you, use inotifywait like the other person suggested.