Get an auto updated symbolic link to the latest file, based on grep on file name

So adapting this SO answer a bit is very close to the solution:

ln -s target-directory/`ls -rt target-directory | grep .log | tail -n1` latest

but how can I actually continously update the sym-link when a new file appears in the directory?

Can this be archived by using inotifywait? How could I install such a job on my system which takes care in the background?

Note that parsing ls output can be error prone. See bash FAQ 99.

If inotifywait tool is available, you can do something like to get update the symlink.

#!/bin/bash

function newest_log
{
    files=(*.log)
    newest=${files[0]}
    for f in "${files[@]}"; do
        if [[ $f -nt $newest ]]; then
            newest=$f
      fi
    done

    echo $newest
}

while inotifywait -e modify target-directory; do
    ln -s target-directory/$(newest_log) latest
done

You can either run this script directly or setup a service like systemd service.