Linux – How to programmatically react to folder changes

If you're lucky enough to be on a debian-based distribution, apt-get install dnotify. Other distributions probably have something similar - look for the dnotify name.

dnotify is a simple program based on Linux kernel 2.4.19+'s dnotify API. dnotify can execute a specified command each time the content of a specific directory changes. It is run from the command line and takes two arguments: one or more directories to monitor and a command to execute whenever a directory has changed. Options control what events to trigger on: when a file was read in the directory, when one was created, deleted and so on.

If you want to handle this within your own program, dnotify is also the API you want to use.

As of GNU coreutils 7.5 released in August 2009, sort allows a -h parameter, which allows numeric suffixes of the kind produced by du -h:

du -hs * | sort -h

If you are using a sort that does not support -h, you can install GNU Coreutils. E.g. on an older Mac OS X:

brew install coreutils
du -hs * | gsort -h

From sort manual:

-h, --human-numeric-sort compare human readable numbers (e.g., 2K 1G)