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.
it automatically removes log files when they are no longer needed.
*** IMPORTANT ***
If you have an existing Nix installation, you must checkpoint the
Nix database to prevent recent transactions from being undone. Do
the following:
- optional: make a backup of $prefix/var/nix/db.
- run `db_checkpoint' from Berkeley DB 4.1:
$ db_checkpoint -h $prefix/var/nix/db -1
- optional (?): run `db_recover' from Berkeley DB 4.1:
$ db_recover -h $prefix/var/nix/db
- remove $prefix/var/nix/db/log* and $prefix/var/nix/db/__db*
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.
