# It goes something like this: ls the packages, grep the names, make them
# unique, find duplicates, sort by version, remove old versions.

# See that gsort (macOS)? $ brew install coreutils
ls `yarn cache dir` | grep -oE "^(npm-[a-z-]+)" | uniq | while read i; do ls -1d "$i"* | grep -E "$i\d" | wc -l | { read c; if (( $c > 1 )); then ls -1d "$i"* | grep -E "$i\d" | gsort -Vr | tail -n +2 | xargs rm -r; fi}; done