print a nice backtrace of the stack, rather than vomiting a gigantic
(and useless) aterm on the screen. Example:
error: while evaluating file `.../pkgs/system/test.nix':
while evaluating attribute `subversion' at `.../pkgs/system/all-packages-generic.nix', line 533:
while evaluating function at `.../pkgs/applications/version-management/subversion/default.nix', line 1:
assertion failed at `.../pkgs/applications/version-management/subversion/default.nix', line 13
Since the Nix expression language is lazy, the trace may be
misleading. The purpose is to provide a hint as to the location of
the problem.
derivation (i.e., the closure store expression) a root of the
garbage collector. This ensures that running `nix-collect-garbage
--no-successors' is safe.
whether we want to upgrade if the current version is less than the
available version (default), when it is less or equal, or always.
* Added a flag `--dry-run' to show what would happen in `--install',
`--uninstall', and `--upgrade', without actually performing the
operation.
of the current profile, e.g.,
$ nix-env --list-generations
...
39 2004-02-02 17:53:53
40 2004-02-02 17:55:18
41 2004-02-02 17:55:41
42 2004-02-02 17:55:50 (current)
$ nix-env --switch-generation 39
$ ls -l /nix/var/nix/profiles/default
... default -> default-39-link
* Also a command `--rollback' which is just a convenience operation to
rollback to the oldest generation younger than the current one.
Note that generations properly form a tree. E.g., if after
switching to generation 39, we perform an installation action,
a generation 43 is created which is a descendant of 39, not 42. So
a rollback from 43 ought to go back to 39. This is not currently
implemented; generations form a linear sequence.
default -> default-94-link
default-82-link -> /nix/store/cc4480...
default-83-link -> /nix/store/caeec8...
...
default-94-link -> /nix/store/2896ca...
experimental -> experimental-2-link
experimental-1-link -> /nix/store/cc4480...
experimental-2-link -> /nix/store/a3148f...
* `--profile' / `-p' -> `--switch-profile' / `-S'
* `--link' / `-l' -> `--profile' / `-p'
* The default profile is stored in $prefix/var/nix/profiles.
$prefix/var/nix/links is gone. Profiles can be stored anywhere.
* The current profile is now referenced from ~/.nix-profile, not
~/.nix-userenv.
* The roots to the garbage collector now have extension `.gcroot', not
`.id'.
the output path of a derivation, not the path of its store
expression. This ensures that changes that affect the path of the
store expression but not the output path, do not affect the
`installed' state of a derivation.
path of the Nix expression to be used with the import, upgrade, and
query commands. For instance,
$ nix-env -I ~/nixpkgs/pkgs/system/i686-linux.nix
$ nix-env --query --available [aka -qa]
sylpheed-0.9.7
bison-1.875
pango-1.2.5
subversion-0.35.1
...
$ nix-env -i sylpheed
$ nix-env -u subversion
There can be only one default at a time.
* If the path to a Nix expression is a symlink, follow the symlink
prior to resolving relative path references in the expression.
the symlink ~/.nix-userenv to the given argument (which defaults to
.../links/current). /etc/profile.d/nix-profile creates this symlink
if it doesn't exist yet. Example use:
$ nix-env -l my_profile -i foo.nix subversion quake
$ nix-env -p my_profile
I don't like the term "profile". Let's deprecate it :-)
nix-env -u foo.nix strategoxt
to replace the installed `strategoxt' derivation with the one from `foo.nix', if
the latter has a higher version number. This is a no-op if `strategoxt' is not
installed. Wildcards are also accepted, so
nix-env -u foo.nix '*'
will replace any installed derivation with newer versions from `foo.nix', if
available.
The notion of "version number" is somewhat ad hoc, but should be useful in most
cases, as evidenced by the following unit tests for the version comparator:
TEST("1.0", "2.3", -1);
TEST("2.1", "2.3", -1);
TEST("2.3", "2.3", 0);
TEST("2.5", "2.3", 1);
TEST("3.1", "2.3", 1);
TEST("2.3.1", "2.3", 1);
TEST("2.3.1", "2.3a", 1);
TEST("2.3pre1", "2.3", -1);
TEST("2.3pre3", "2.3pre12", -1);
TEST("2.3a", "2.3c", -1);
TEST("2.3pre1", "2.3c", -1);
TEST("2.3pre1", "2.3q", -1);
(-1 = less, 0 = equal, 1 = greater)
* A new verbosity level `lvlInfo', between `lvlError' and `lvlTalkative'. This is
the default for `nix-env', so without any `-v' flags users should get useful
output, e.g.,
$ nix-env -u foo.nix strategoxt
upgrading `strategoxt-0.9.2' to `strategoxt-0.9.3'
