Example:

===
[root@dutibo:~]# nix-channel –update
obtaining list of Nix archives at `http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable/MANIFEST.bz2’…

4539 store paths in manifest
downloading Nix expressions from `http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable/nixexprs.tar.bz2’…

unpacking channel Nix expressions…
the following derivations will be built:
/nix/store/7yddwdkd4y416mfh4j62jv5ixc3ic2ig-channels.drv
building path(s) /nix/store/f3kks1kf6r77wdpgi7r5byfqksrxfm94-channels' /nix/store/vksjjibg8zl1gs1pkarw43wg6fqhk4k4-unpack.sh: line 3: /nix/store/68afga4khv0ws37n00qy06m11srx1lhj-coreutils-6.12/bin/mkdir: No such file or directory builder for/nix/store/7yddwdkd4y416mfh4j62jv5ixc3ic2ig-channels.drv’ failed with exit code 1
error: build of `/nix/store/7yddwdkd4y416mfh4j62jv5ixc3ic2ig-channels.drv’ failed
cannot realise store expression at /var/run/current-system/sw/bin/nix-channel line 135.
===

This is because /nix/store/68afga4khv0ws37n00qy06m11srx1lhj-coreutils-6.12 is not an explicit dependency of the unpack derivation, so the path doesn’t appear in the chroot. Argh.

Incidentally this means that nix-channel is also likely to fail in distributed environments.

Submitted on 18 December 2008 at 17:50