Nix-env failed to call addPermRoot(), which is necessary to safely
add a new root. So if nix-env started after and finished before the
garbage collector, the user environment (plus all other new stuff)
it built might be garbage collected, leading to a dangling symlink
chain in ~/.nix-profile...
* Be more explicit if we block on the GC lock ("waiting for the big
garbage collector lock...").
* Don't loop trying to create a new generation. It's not necessary
anymore since profiles are locked nowadays.
https://svn.cs.uu.nl:12443/repos/trace/buildfarm-control/trunk/ext/nix/,
with some modifications. This allows `nix-env -qa' to show the
attribute path that can be used to unambiguously install a package
using `nix-env -i -A'. Example:
$ nix-env -f top-level/all-packages.nix -qaA subversion xorg-server
subversionWithJava subversion-1.2.3
subversion subversion-1.3.2
subversion14 subversion-1.4.0pre-rc1
xorg.xorgserver xorg-server-1.1.0
e.g.,
$ nix-env -i -A subversion xorg.xorgserver
The main advantage over using symbolic names is that using attribute
names is unambiguous and much, much faster.
packages (provided that they have a `meta.description' attribute).
E.g.,
$ ./src/nix-env/nix-env -qa --description gcc
gcc-4.0.2 GNU Compiler Collection, 4.0.x (cross-compiler for sparc-linux)
gcc-4.0.2 GNU Compiler Collection, 4.0.x (cross-compiler for mips-linux)
gcc-4.0.2 GNU Compiler Collection, 4.0.x (cross-compiler for arm-linux)
gcc-4.0.2 GNU Compiler Collection, 4.0.x
to be queried, e.g., `nix-env -qa firefox'. This does require the
argument '*' to be passed if one wants information about all
derivations, so the old `nix-env -qa' now is `nix-env -qa "*"'.
expressions that cause an assertion failure (like `assert system ==
"i686-linux"'). This allows all-packages.nix in Nixpkgs to be used
on all platforms, even if some Nix expressions don't work on all
platforms.
Not sure if this is a good idea; it's a bit hacky. In particular,
due to laziness some derivations might appear in `nix-env -qa' but
disappear in `nix-env -qas' or `nix-env -i'.
Commit 5000!
with the same name *and* version number, and pick the first one
(this means that the order in which channels appear in
~/.nix-channels matters). E.g.:
$ nix-env ii aterm
warning: there are multiple derivations named `aterm-2.4.2'; using the first one
installing `aterm-2.4.2'
versions to available versions, or vice versa.
For example, the following compares installed versions to available
versions:
$ nix-env -qc
autoconf-2.59 = 2.59
automake-1.9.4 < 1.9.6
f-spot-0.0.10 - ?
firefox-1.0.4 < 1.0.7
...
I.e., there are newer versions available (in the current default Nix
expression) for Automake and Firefox, but not for Autoconf, and
F-Spot is missing altogether.
Conversely, the available versions can be compared to the installed
versions:
$ nix-env -qac
autoconf-2.59 = 2.59
automake-1.9.6 > 1.9.4
bash-3.0 - ?
firefox-1.0.7 > 1.0.4
...
Note that bash is available but no version of it is installed.
If multiple versions are available for comparison, then the highest
is used. E.g., if Subversion 1.2.0 is installed, and Subversion
1.1.4 and 1.2.3 are available, then `nix-env -qc' will print `<
1.2.3', not `> 1.1.4'.
If higher versions are available, the version column is printed in
red (using ANSI escape codes).
environment elements from one user environment to another, e.g.,
$ nix-env -i --from-profile /nix/var/nix/profiles/other-profile aterm
copies the `aterm' component installed in the `other-profile' to the
user's current profile.
user environment, e.g.,
$ nix-env -i /nix/store/z58v41v21xd3ywrqk1vmvdwlagjx7f10-aterm-2.3.1.drv
or
$ nix-env -i /nix/store/hsyj5pbn0d9iz7q0aj0fga7cpaadvp1l-aterm-2.3.1
This is useful because it allows Nix expressions to be bypassed
entirely. For instance, if only a nix-pull manifest is provided,
plus the top-level path of some component, it can be installed
without having to supply the Nix expression (e.g., for obfuscation,
or to be independent of Nix expression language changes or context
dependencies).
install derivations from a Nix expression specified on the command
line. This is particularly useful for disambiguation if there are
multiple derivations with the same name. For instance, in Nixpkgs,
to install the Firefox wrapper rather than the plain Firefox
component:
$ nix-env -f .../i686-linux.nix -i -E 'x: x.firefoxWrapper'
The Nix expressions should be functions to which the default Nix
expression (in this case, `i686-linux.nix') is passed, hence `x:
...'.
This might also be a nice way to deal with high-level (user-level)
variability, e.g.,
$ nix-env -f ./server.nix -i -E 'x: x {port = 8080; ssl = false;}'
to derivations in user environments. Nice for developers (since it
prevents build-time-only dependencies from being GC'ed, in
conjunction with `gc-keep-outputs'). Turned off by default.
