Answer by awi for Remove all files except some from a directory

find [path] -type f -not -name 'textfile.txt' -not -name 'backup.tar.gz' -delete

If you don't specify -type f find will also list directories, which you may not want.

Or a more general solution using the very useful combination find | xargs:

find [path] -type f -not -name 'EXPR' -print0 | xargs -0 rm --

for example, delete all non txt-files in the current directory:

find . -type f -not -name '*txt' -print0 | xargs -0 rm --

The print0 and -0 combination is needed if there are spaces in any of the filenames that should be deleted.