>The master branch of the linux kernel has a little bit over 1 million commits (measured with git log --format=oneline | wc -l). The master branch is irrelevan

>The master branch of the linux kernel has a little bit over 1 million commits (measured with git log --format=oneline | wc -l). The master branch is irrelevant - github links to commits don't include the branch (and the way git works, commits don't really have "a branch"): https://github.com/torvalds/linux/commit/ac632c504d0b881d7cfb44e3fdde3ec30eb548d9 https://github.com/torvalds/linux/commit/ac632c504d0b881d7cf... >With "git log --format=oneline | cut -b 1-4 | uniq -c | sort -n | tail -n30" you can verify that it has 25 prefix collisions with a 4 character prefix. With 5 it's still 4 collisions, with 6 there are none. I'm sorry to say, your script doesn't work. You need to `sort` before `uniq` as that only counts adjacent duplicates. The linux kernel as of 5.12-rc1 had 25 prefix collisions for the prefix "ffeb" alone (and 33 for "e3f2"). Here are the full shas: ffeb03cfe2b49b73da7b325a31714003761fc6d5 ffebecd9d49542046c5ecbb410af01e016636e19 ffeb1e9e897b8d36b197275592d121c96d3bdb95 ffebbecaaa86f7cde4a6a813bed14f9d56e7c373 ffeb595d84811dde16a28b33d8a7cf26d51d51b3 ffebbaedc8616cffe648202e364dce6a045d65a2 ffebe74b7c95a41d2d0ac70a44d410e0efa37ad8 ffebc8c0344934db710afc76e3bfda11a823bb3d ffebb83b34f843aadcbd3e03c4e449da14d0870d ffeb6437f018f072a330ad5911036fd020b35ac3 ffeb883e5662e94b14948078e85812261277ad67 ffebf5f391dfa9da3e086abad3eef7d3e5300249 ffebfc364dcaa5dea1a589d42207834b028df789 ffeb13aab68e2d0082cbb147dc765beb092f83f4 ffebeb46dd34736c90ffbca1ccb0bef8f4827c44 ffeb40515971c9860ff671bb074689db15e18831 ffebad7948ee0e9c619ae6e87d99437d907fc7e3 ffeb501c6cba803eefc46b570feccffe61a6d883 ffeb33d20c6217bb8f0ab46d3f1396021c00c24f ffeb80fc30acbf6bd51cb47a1815f621a9d017dc ffeb414a59291d5891f09727beb793c109f19f08 ffebedb7ab3f7964a70a1771547b26af38a189d2 ffebabe0bf0de9ee500d4605d6acb71e1ee3b79f ffeb9ec72e18e16d0b0835d959cdf01650758638 ffeb874b2b893aea7d10b0b088e06a7b1ded2a3e with 5 characters there are 8 for b91e1. With 6 characters there are 5 for 120bda: 120bdafaece72056e48d97809c5abe172824a7f6 120bdac7376a36418eb1d55e0161dc0e660a45c3 120bdaa47cdd1ca37ce938c888bb08e33e6181a8 120bda35ff8514c937dac6d4e5c7dc6c01c699ac 120bda20c6f64b32e8bfbdd7b34feafaa5f5332e and a total of 28606 colliding 6-digit prefixes. There are 9 colliding 9-digit prefixes and no 10-digit prefix. (found with `git rev-list --all --no-abbrev-commit | sort | cut -b 1-4 | uniq -c` and variations on that theme)