Nix. This is to prevent Berkeley DB from becoming wedged.
Unfortunately it is not possible to throw C++ exceptions from a
signal handler. In fact, you can't do much of anything except
change variables of type `volatile sig_atomic_t'. So we set an
interrupt flag in the signal handler and check it at various
strategic locations in the code (by calling checkInterrupt()).
Since this is unlikely to cover all cases (e.g., (semi-)infinite
loops), sometimes SIGTERM may now be required to kill Nix.
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.
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'
