So for instance "nix copy --to ... nixpkgs.hello" will build
nixpkgs.hello first. It's debatable whether this is a good idea. It
seems desirable for commands like "nix copy" but maybe not for
commands like "nix path-info".
Thus
$ nix build -f foo.nix
will build foo.nix.
And
$ nix build
will build default.nix. However, this may not be a good idea because
it's kind of inconsistent, given that "nix build foo" will build the
"foo" attribute from the default installation source (i.e. the
synthesis of $NIX_PATH), rather than ./default.nix. So I may revert
this.
This allows commands like 'nix path-info', 'nix copy', 'nix verify'
etc. to work on arbitrary installables. E.g. to copy geeqie to a
binary cache:
$ nix copy -r --to file:///tmp/binary-cache nixpkgs.geeqie
Or to get the closure size of thunderbird:
$ nix path-info -S nixpkgs.thunderbird
This writes info about every path in the closure in the same format as
‘nix path-info --json’. Thus it also includes NAR hashes and sizes.
Example:
[
{
"path": "/nix/store/10h6li26i7g6z3mdpvra09yyf10mmzdr-hello-2.10",
"narHash": "sha256:0ckdc4z20kkmpqdilx0wl6cricxv90lh85xpv2qljppcmz6vzcxl",
"narSize": 197648,
"references": [
"/nix/store/10h6li26i7g6z3mdpvra09yyf10mmzdr-hello-2.10",
"/nix/store/27binbdy296qvjycdgr1535v8872vz3z-glibc-2.24"
],
"closureSize": 20939776
},
{
"path": "/nix/store/27binbdy296qvjycdgr1535v8872vz3z-glibc-2.24",
"narHash": "sha256:1nfn3m3p98y1c0kd0brp80dn9n5mycwgrk183j17rajya0h7gax3",
"narSize": 20742128,
"references": [
"/nix/store/27binbdy296qvjycdgr1535v8872vz3z-glibc-2.24"
],
"closureSize": 20742128
}
]
Fixes#1134.
That is, unless --file is specified, the Nix search path is
synthesized into an attribute set. Thus you can say
$ nix build nixpkgs.hello
assuming $NIX_PATH contains an entry of the form "nixpkgs=...". This
is more verbose than
$ nix build hello
but is less ambiguous.
This is a convenience command to allow users who are not privileged to
create /nix/store to use Nix with regular binary caches. For example,
$ NIX_REMOTE="local?state=$HOME/nix/var&real=/$HOME/nix/store" nix run firefox bashInteractive
will download Firefox and bash from cache.nixos.org, then start a
shell in which $HOME/nix/store is mounted on /nix/store.
This replaces nix-push. For example,
$ nix copy --to file:///tmp/cache -r $(type -p firefox)
copies the closure of firefox to the specified binary cache. And
$ nix copy --from file:///tmp/cache --to s3://my-cache /nix/store/abcd...
copies between two binary caches.
It will also replace nix-copy-closure, once we have an SSHStore class,
e.g.
$ nix copy --from ssh://alice@machine /nix/store/abcd...
