Linux

The Linux way:

• write a script: you can use the find command to find for example rars in a folder. find ~/thatfolder -iname '*.rar' -exec uncompresscommand. Read 'man find' for specifics. Script's first line is #!/bin/bash. Say 'chmod u+x script' to make it executable.

• set up a systemd timer unit that calls a service unit that runs your script at intervals.

• you can use something like for file in ~/thatfolder/* ; do sed trick that extracts the file extension and puts it in a variable ; case $variable in ; bunch of cases for different extensions. Variable $file will hold the source file name. Read up on bash scripting to figure it out.

Welcome to penguinland :D

It might be possible with inotify.

Sounds like a nifty program. Is this something you use a lot? What's the use case? While I know extracting files is not difficult in Linux, there are a lot of different compressed file types. Most have some Linux alternative. Linux is different from windows, in that most things that require a separate program to be installed, are usually default operations. Most file managers offer to compress or extract in the right click menu. Try a live distro for a few days. It will blow your mind.

syncthing might also be slightly relevant?