lix/doc/manual/rl-next/leading-period.md

---
synopsis: Store paths are allowed to start with `.`
issues: 912
prs: [9867, 9091, 9095, 9120, 9121, 9122, 9130, 9219, 9224]
---

Leading periods were allowed by accident in Nix 2.4. The Nix team has considered this to be a bug, but this behavior has since been relied on by users, leading to unnecessary difficulties.
From now on, leading periods are officially, definitively supported. The names `.` and `..` are disallowed, as well as those starting with `.-` or `..-`.

Nix versions that denied leading periods are documented [in the issue](https://github.com/NixOS/nix/issues/912#issuecomment-1919583286).
parseStorePath: Support leading period (cherry picked from commit b13e6a76b4f289c6db69ffaa7bd35b7e44f2a391) Change-Id: Ie14be437d87d17248f80e1f009aa2a4311ddede6 2024-01-27 10:19:05 +00:00			`---`
			synopsis: Store paths are allowed to start with `.`
			`issues: 912`
			`prs: [9867, 9091, 9095, 9120, 9121, 9122, 9130, 9219, 9224]`
			`---`

			`Leading periods were allowed by accident in Nix 2.4. The Nix team has considered this to be a bug, but this behavior has since been relied on by users, leading to unnecessary difficulties.`
Disallow store path names that are . or .. (plus opt. -) As discussed in the maintainer meeting on 2024-01-29. Mainly this is to avoid a situation where the name is parsed and treated as a file name, mostly to protect users. .-* and ..-* are also considered invalid because they might strip on that separator to remove versions. Doesn't really work, but that's what we decided, and I won't argue with it, because .-* probably doesn't seem to have a real world application anyway. We do still permit a 1-character name that's just "-", which still poses a similar risk in such a situation. We can't start disallowing trailing -, because a non-zero number of users will need it and we've seen how annoying and painful such a change is. What matters most is preventing a situation where . or .. can be injected, and to just get this done. (cherry picked from commit f1b4663805a9dbcb1ace64ec110092d17c9155e0) Change-Id: I900a8509933cee662f888c3c76fa8986b0058839 2024-01-30 17:37:23 +00:00			From now on, leading periods are officially, definitively supported. The names `.` and `..` are disallowed, as well as those starting with `.-` or `..-`.
parseStorePath: Support leading period (cherry picked from commit b13e6a76b4f289c6db69ffaa7bd35b7e44f2a391) Change-Id: Ie14be437d87d17248f80e1f009aa2a4311ddede6 2024-01-27 10:19:05 +00:00
			`Nix versions that denied leading periods are documented [in the issue](https://github.com/NixOS/nix/issues/912#issuecomment-1919583286).`