mirror of
https://github.com/privatevoid-net/nix-super.git
synced 2024-11-22 14:06:16 +02:00
* Update the user environments figure to show multiple profiles and
users. * Change to base-32 hashes.
This commit is contained in:
parent
afc3a7b79b
commit
f982df3cd7
4 changed files with 52 additions and 53 deletions
Binary file not shown.
Before Width: | Height: | Size: 16 KiB After Width: | Height: | Size: 83 KiB |
BIN
doc/manual/figures/user-environments.sxd
Normal file
BIN
doc/manual/figures/user-environments.sxd
Normal file
Binary file not shown.
|
@ -5,8 +5,8 @@
|
|||
|
||||
<para>The easiest way to obtain Nix is to download a <ulink
|
||||
url='http://www.cs.uu.nl/groups/ST/Trace/Nix'>source
|
||||
distribution</ulink>. RPMs for Red Hat 9 are also available. These
|
||||
distributions are generated automatically.</para>
|
||||
distribution</ulink>. RPMs for Red Hat, SuSE, and Fedore Core are
|
||||
also available.</para>
|
||||
|
||||
<para>Alternatively, the most recent sources of Nix can be obtained
|
||||
from its <ulink
|
||||
|
|
|
@ -2,7 +2,7 @@
|
|||
|
||||
<para>This chapter discusses how to do package management with Nix,
|
||||
i.e., how to obtain, install, upgrade, and erase components. This is
|
||||
the <quote>user's</quote> perspective of the Nix system — people
|
||||
the <quote>user’s</quote> perspective of the Nix system — people
|
||||
who want to <emphasis>create</emphasis> components should consult
|
||||
<xref linkend='chap-writing-nix-expressions' />.</para>
|
||||
|
||||
|
@ -19,7 +19,7 @@ on the set of installed applications. That is, there might be lots of
|
|||
applications present on the system (possibly in many different
|
||||
versions), but users can have a specific selection of those active —
|
||||
where <quote>active</quote> just means that it appears in a directory
|
||||
in the user's <envar>PATH</envar>. Such a view on the set of
|
||||
in the user’s <envar>PATH</envar>. Such a view on the set of
|
||||
installed applications is called a <emphasis>user
|
||||
environment</emphasis>, which is just a directory tree consisting of
|
||||
symlinks to the files of the active applications. </para>
|
||||
|
@ -52,7 +52,7 @@ bzip2-1.0.2
|
|||
...</screen>
|
||||
|
||||
where <literal>nixpkgs-<replaceable>version</replaceable></literal> is
|
||||
where you've unpacked the release.</para>
|
||||
where you’ve unpacked the release.</para>
|
||||
|
||||
<para>It is also possible to see the <emphasis>status</emphasis> of
|
||||
available components, i.e., whether they are installed into the user
|
||||
|
@ -72,7 +72,7 @@ component is installed in your current user environment. The second
|
|||
(in which case installing it into your user environment would be a
|
||||
very quick operation). The last one (<literal>S</literal>) indicates
|
||||
whether there is a so-called <emphasis>substitute</emphasis> for the
|
||||
component, which is Nix's mechanism for doing binary deployment. It
|
||||
component, which is Nix’s mechanism for doing binary deployment. It
|
||||
just means that Nix know that it can fetch a pre-built component from
|
||||
somewhere (typically a network server) instead of building it
|
||||
locally.</para>
|
||||
|
@ -98,7 +98,7 @@ available somewhere. This is done using the
|
|||
<command>nix-pull</command> command, which must be supplied with a URL
|
||||
containing a <emphasis>manifest</emphasis> describing what binaries
|
||||
are available. This URL should correspond to the Nix Packages release
|
||||
that you're using. For instance, if you obtained a release from
|
||||
that you’re using. For instance, if you obtained a release from
|
||||
<ulink
|
||||
url='http://catamaran.labs.cs.uu.nl/dist/nix/nixpkgs-0.6pre1554/' />,
|
||||
then you should do:
|
||||
|
@ -111,7 +111,7 @@ downloading binaries from <systemitem
|
|||
class='fqdomainname'>catamaran.labs.cs.uu.nl</systemitem>, instead of
|
||||
building them from source. This might still take a while since all
|
||||
dependencies must be downloaded, but on a reasonably fast connection
|
||||
such as an DSL line it's on the order of a few minutes.</para>
|
||||
such as an DSL line it’s on the order of a few minutes.</para>
|
||||
|
||||
<para>Naturally, packages can also be uninstalled:
|
||||
|
||||
|
@ -129,7 +129,7 @@ $ nix-env -f nixpkgs-<replaceable>version</replaceable> -u subversion</screen>
|
|||
This will <emphasis>only</emphasis> upgrade Subversion if there is a
|
||||
<quote>newer</quote> version in the new set of Nix expressions, as
|
||||
defined by some pretty arbitrary rules regarding ordering of version
|
||||
numbers (which generally do what you'd expect of them). To just
|
||||
numbers (which generally do what you’d expect of them). To just
|
||||
unconditionally replace Subversion with whatever version is in the Nix
|
||||
expressions, use <parameter>-i</parameter> instead of
|
||||
<parameter>-u</parameter>; <parameter>-i</parameter> will remove
|
||||
|
@ -143,7 +143,7 @@ $ nix-env -f nixpkgs-<replaceable>version</replaceable> -u '*'</screen>
|
|||
|
||||
</para>
|
||||
|
||||
<para>Sometimes it's useful to be able to ask what
|
||||
<para>Sometimes it’s useful to be able to ask what
|
||||
<command>nix-env</command> would do, without actually doing it. For
|
||||
instance, to find out what packages would be upgraded by
|
||||
<literal>nix-env -u '*'</literal>, you can do
|
||||
|
@ -177,28 +177,26 @@ set.</para></footnote></para>
|
|||
|
||||
<sect1><title>Profiles</title>
|
||||
|
||||
<para>Profiles and user environments are Nix's mechanism for
|
||||
<para>Profiles and user environments are Nix’s mechanism for
|
||||
implementing the ability to allow differens users to have different
|
||||
configurations, and to do atomic upgrades and rollbacks. To
|
||||
understand how they work, it's useful to know a bit about how Nix
|
||||
understand how they work, it’s useful to know a bit about how Nix
|
||||
works. In Nix, components are stored in unique locations in the
|
||||
<emphasis>Nix store</emphasis> (typically,
|
||||
<filename>/nix/store</filename>). For instance, a particular version
|
||||
of the Subversion component might be stored in a directory
|
||||
<filename>/nix/store/eeeeaf42e56b...-subversion-0.32.1/</filename>,
|
||||
<filename>/nix/store/dpmvp969yhdqs7lm2r1a3gng7pyq6vy4-subversion-1.1.3/</filename>,
|
||||
while another version might be stored in
|
||||
<filename>/nix/store/58823d558a6a...-subversion-0.34/</filename>. The
|
||||
long hexadecimal numbers prefixed to the directory names are
|
||||
cryptographic hashes<footnote><para>160-bit truncations of SHA-256
|
||||
hashes, to be precise.</para></footnote> of <emphasis>all</emphasis>
|
||||
inputs involved in building the component — sources, dependencies,
|
||||
compiler flags, and so on. So if two components differ in any way,
|
||||
they end up in different locations in the file system, so they don't
|
||||
interfere with each other. <xref linkend='fig-user-environments'
|
||||
/><footnote><para>TODO: the figure isn't entirely up to date. It
|
||||
should show multiple profiles and
|
||||
<filename>~/.nix-profile</filename>.</para></footnote> shows a part of
|
||||
a typical Nix store.</para>
|
||||
<filename>/nix/store/5mq2jcn36ldlmh93yj1n8s9c95pj7c5s-subversion-1.1.2</filename>.
|
||||
The long strings prefixed to the directory names are cryptographic
|
||||
hashes<footnote><para>160-bit truncations of SHA-256 hashes encoded in
|
||||
a base-32 notation, to be precise.</para></footnote> of
|
||||
<emphasis>all</emphasis> inputs involved in building the component —
|
||||
sources, dependencies, compiler flags, and so on. So if two
|
||||
components differ in any way, they end up in different locations in
|
||||
the file system, so they don’t interfere with each other. <xref
|
||||
linkend='fig-user-environments' /> shows a part of a typical Nix
|
||||
store.</para>
|
||||
|
||||
<figure id='fig-user-environments'><title>User environments</title>
|
||||
<mediaobject>
|
||||
|
@ -208,41 +206,42 @@ a typical Nix store.</para>
|
|||
</mediaobject>
|
||||
</figure>
|
||||
|
||||
<para>Of course, you wouldn't want to type
|
||||
<para>Of course, you wouldn’t want to type
|
||||
|
||||
<screen>
|
||||
$ /nix/store/eeeeaf42e56b...-subversion-0.32.1/bin/svn</screen>
|
||||
$ /nix/store/dpmvp969yhdq...-subversion-1.1.3/bin/svn</screen>
|
||||
|
||||
every time you want to run Subversion. Of course we could set up the
|
||||
<envar>PATH</envar> environment variable to include the
|
||||
<filename>bin</filename> directory of every component we want to use,
|
||||
but this is not very convenient since changing <envar>PATH</envar>
|
||||
doesn't take effect for already existing processes. The solution Nix
|
||||
doesn’t take effect for already existing processes. The solution Nix
|
||||
uses is to create directory trees of symlinks to
|
||||
<emphasis>activated</emphasis> components. These are called
|
||||
<emphasis>user environments</emphasis> and they are components
|
||||
themselves (though automatically generated by
|
||||
<command>nix-env</command>), so they too reside in the Nix store. For
|
||||
instance, in <xref linkend='fig-user-environments' /> the user
|
||||
environment <filename>/nix/store/068150f63831...-user-env</filename>
|
||||
contains a symlink to just Subversion 0.32.1 (arrows in the figure
|
||||
environment <filename>/nix/store/5mq2jcn36ldl...-user-env</filename>
|
||||
contains a symlink to just Subversion 1.1.2 (arrows in the figure
|
||||
indicate symlinks). This would be what we would obtain if we had done
|
||||
|
||||
<screen>
|
||||
$ nix-env -i subversion</screen>
|
||||
|
||||
on a set of Nix expressions that contained Subversion 0.32.1.</para>
|
||||
on a set of Nix expressions that contained Subversion 1.1.2.</para>
|
||||
|
||||
<para>This doesn't in itself solve the problem, of course; you
|
||||
wouldn't want to type
|
||||
<filename>/nix/store/068150f63831...-user-env/bin/svn</filename>
|
||||
either. Therefore there are symlinks outside of the store that point
|
||||
<para>This doesn’t in itself solve the problem, of course; you
|
||||
wouldn’t want to type
|
||||
<filename>/nix/store/0c1p5z4kda11...-user-env/bin/svn</filename>
|
||||
either. That’s why there are symlinks outside of the store that point
|
||||
to the user environments in the store; for instance, the symlinks
|
||||
<filename>42</filename> and <filename>43</filename> in the example.
|
||||
These are called <emphasis>generations</emphasis> since every time you
|
||||
perform a <command>nix-env</command> operation, a new user environment
|
||||
is generated based on the current one. For instance, generation 43
|
||||
was created from generation 42 when we did
|
||||
<filename>default-42-link</filename> and
|
||||
<filename>default-43-link</filename> in the example. These are called
|
||||
<emphasis>generations</emphasis> since every time you perform a
|
||||
<command>nix-env</command> operation, a new user environment is
|
||||
generated based on the current one. For instance, generation 43 was
|
||||
created from generation 42 when we did
|
||||
|
||||
<screen>
|
||||
$ nix-env -i subversion mozilla</screen>
|
||||
|
@ -251,14 +250,14 @@ on a set of Nix expressions that contained Mozilla and a new version
|
|||
of Subversion.</para>
|
||||
|
||||
<para>Generations are grouped together into
|
||||
<emphasis>profiles</emphasis> so that different users don't interfere
|
||||
with each other if they don't want to. For example:
|
||||
<emphasis>profiles</emphasis> so that different users don’t interfere
|
||||
with each other if they don’t want to. For example:
|
||||
|
||||
<screen>
|
||||
$ ls -l /nix/var/nix/profiles/
|
||||
...
|
||||
lrwxrwxrwx 1 eelco ... default-42-link -> /nix/store/068150f63831...-user-env
|
||||
lrwxrwxrwx 1 eelco ... default-43-link -> /nix/store/84c85f89ddbf...-user-env
|
||||
lrwxrwxrwx 1 eelco ... default-42-link -> /nix/store/0c1p5z4kda11...-user-env
|
||||
lrwxrwxrwx 1 eelco ... default-43-link -> /nix/store/3aw2pdyx2jfc...-user-env
|
||||
lrwxrwxrwx 1 eelco ... default -> default-43-link</screen>
|
||||
|
||||
This shows a profile called <filename>default</filename>. The file
|
||||
|
@ -268,7 +267,7 @@ operation, a new user environment and generation link are created
|
|||
based on the current one, and finally the <filename>default</filename>
|
||||
symlink is made to point at the new generation. This last step is
|
||||
atomic on Unix, which explains how we can do atomic upgrades. (Note
|
||||
that the building/installing of new components doesn't interfere in
|
||||
that the building/installing of new components doesn’t interfere in
|
||||
any way with old components, since they are stored in different
|
||||
locations in the Nix store.)</para>
|
||||
|
||||
|
@ -293,13 +292,13 @@ can also see all available generations:
|
|||
$ nix-env --list-generations</screen></para>
|
||||
|
||||
<para>Actually, there is another level of indirection not shown in the
|
||||
figure above. You generally wouldn't have
|
||||
figure above. You generally wouldn’t have
|
||||
<filename>/nix/var/nix/profiles/<replaceable>some-profile</replaceable>/bin</filename>
|
||||
in your <envar>PATH</envar>. Rather, there is a symlink
|
||||
<filename>~/.nix-profile</filename> that points to your current
|
||||
profile. This means that you should put
|
||||
<filename>~/.nix-profile/bin</filename> in your <envar>PATH</envar>
|
||||
(and indeed, that's what the initialisation script
|
||||
(and indeed, that’s what the initialisation script
|
||||
<filename>/nix/etc/profile.d/nix.sh</filename> does). This makes it
|
||||
easier to switch to a different profile. You can do that using the
|
||||
command <command>nix-env --switch-profile</command>:
|
||||
|
@ -310,7 +309,7 @@ $ nix-env --switch-profile /nix/var/nix/profiles/my-profile
|
|||
$ nix-env --switch-profile /nix/var/nix/profiles/default</screen>
|
||||
|
||||
These commands switch to the <filename>my-profile</filename> and
|
||||
default profile, respectively. If the profile doesn't exist, it will
|
||||
default profile, respectively. If the profile doesn’t exist, it will
|
||||
be created automatically. You should be careful about storing a
|
||||
profile in another location than the <filename>profiles</filename>
|
||||
directory, since otherwise it might not be used as a root of the
|
||||
|
@ -346,7 +345,7 @@ not used (directly or indirectly) by any generation of any
|
|||
profile.</para>
|
||||
|
||||
<para>Note however that as long as old generations reference a
|
||||
component, it will not be deleted. After all, we wouldn't be able to
|
||||
component, it will not be deleted. After all, we wouldn’t be able to
|
||||
do a rollback otherwise. So in order for garbage collection to be
|
||||
effective, you should also delete (some) old generations. Of course,
|
||||
this should only be done if you are certain that you will not need to
|
||||
|
@ -378,7 +377,7 @@ You can alo first view what files would be deleted:
|
|||
$ nix-collect-garbage --print-dead</screen>
|
||||
|
||||
Likewise, the option <option>--print-live</option> will show the paths
|
||||
that <emphasis>won't</emphasis> be deleted.</para>
|
||||
that <emphasis>won’t</emphasis> be deleted.</para>
|
||||
|
||||
<sect2><title>Garbage collector roots</title>
|
||||
|
||||
|
@ -402,11 +401,11 @@ so all generations of all profiles are also roots of the collector.</para>
|
|||
|
||||
<sect1><title>Channels</title>
|
||||
|
||||
<para>If you want to stay up to date with a set of packages, it's not
|
||||
<para>If you want to stay up to date with a set of packages, it’s not
|
||||
very convenient to manually download the latest set of Nix expressions
|
||||
for those packages, use <command>nix-pull</command> to register
|
||||
pre-built binaries (if available), and upgrade using
|
||||
<command>nix-env</command>. Fortunately, there's a better way:
|
||||
<command>nix-env</command>. Fortunately, there’s a better way:
|
||||
<emphasis>Nix channels</emphasis>.</para>
|
||||
|
||||
<para>A Nix channel is just a URL that points to a place that contains
|
||||
|
@ -440,7 +439,7 @@ This downloads the Nix expressions in every channel (downloaded from
|
|||
and registers any available pre-built binaries in every channel
|
||||
(by <command>nix-pull</command>ing
|
||||
<literal><replaceable>url</replaceable>/MANIFEST</literal>). It also
|
||||
makes the union of each channel's Nix expressions the default for
|
||||
makes the union of each channel’s Nix expressions the default for
|
||||
<command>nix-env</command> operations. Consequently, you can then say
|
||||
|
||||
<screen>
|
||||
|
|
Loading…
Reference in a new issue