Nix: The ManualIntroductionThe problem space
Nix is a system for controlling the automatic creation and distribution
of data, such as computer programs and other software artifacts. This
is a very general problem, and there are many applications that fall
under this description.
Build management
Build management tools are used to perform software
builds, that is, the construction of derived products
such as executable programs from source code. A commonly used build
tool is Make, which is a standard tool on Unix systems. These tools
have to deal with several issues:
Package management
After software has been built, is must also be
deployed in the intended target environment,
e.g., the user's workstation. Examples include the Red Hat package
manager (RPM), Microsoft's MSI, and so on. Here also we have to deal
with several issues:
The creation of packages from some formal
description of what artifacts should be distributed in the
package.
The deployment of packages, that is, the
mechanism by which we get them onto the intended target
environment. This can be as simple as copying a file, but
complexity comes from the wide range of possible installation
media (such as a network install), and the scalability of the
process (if a program must be installed on a thousand systems,
we do not want to visit each system and perform some manual
steps to install the program on that system; that is, the
complexity for the system administrator should be constant, not
linear).
The Nix system
...
Existing tools in this field generally both a underlying model (such as
the derivation graph of build tools, or the versioning scheme that
determines when two packages are compatible in a package
management system) and a formalism that allows ...
Following the principle of separation of mechanism and policy, the Nix
system separates the low-level aspect of file
system object management form the high-level
aspect of the ...
A Guided Tour
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Fix Language Reference
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Nix Syntax and Semantics
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InstallationPrerequisites
Nix uses Sleepycat's Berkeley DB and CWI's ATerm library. However,
these are fetched automatically as part of the build process.
Other than that, you need a good C++ compiler. GCC 2.95 does not
appear to work; please use GCC 3.x.
Obtaining Nix
Nix can be obtained from its Subversion
repository. For example, the following command will check
out the latest revision into a directory called
nix:
$ svn checkout http://losser.st-lab.cs.uu.nl:12080/repos/trace/nix/trunk nix
Likewise, specific releases can be obtained from the tags
directory of the repository. If you don't have Subversion,
you can download a compressed
tar-file of the latest revision of the repository.
Building Nix
To build Nix, do the following:
$ autoreconf -i
$ ./configure options...
$ make
$ make install
Currently, the only useful switch for configure is
to specify
where Nix is to be installed. The default installation directory is
/nix. You can change this to any location you
like. You should ensure that you have write permission to the
installation prefix.
It is advisable not to change the installation
prefix, since doing so will in all likelihood make it impossible to
use derivates built on other systems.
TroubleshootingDatabase hangs
If Nix or Fix appear to hang immediately after they are started, Nix's
database is probably wedged, i.e., some process died
while it held a lock on the database. The solution is to ensure that
no other processes are accessing the database and then run the
following command:
$ db_recover -e -h prefix/var/nix/db
Here, prefix should be replaced by Nix's
installation prefix.
Database logfile removal
Every time a Nix database transaction takes place, Nix writes a record
of this transaction to a log in its database
directory to ensure that the operation can be replayed in case of a
application or system crash. However, without manual intervention,
the log grows indefinitely. Hence, unused log files should be deleted
periodically. This can be accomplished using the following command:
$ rm `db_archive -a -h prefix/var/nix/db`Known problems
Nix should automatically recover the Berkeley DB database.
Nix should automatically remove Berkeley DB logfiles.