NixOS Wiki

Terms and Definitions in Nix Project: Difference between revisions

← Older edit
VisualWikitext
imported>Nix
order most important items more prominently. better explain profiles and generations
Mayer (talk | contribs)
328 edits
No edit summary
 
(17 intermediate revisions by 6 users not shown)
Line 1: Line 1:
 
<languages/>
== Terms and Definitions ==
<translate>
 
<!--T:1-->
If you come across a term or word you don't know, add it here.
If you come across a term or word you don't know, add it here.


<!--T:2-->
<!-- README: Rows in this table with named divs have been linked to in other pages. Avoid renaming or removing any of the divs. -->
<!-- README: Rows in this table with named divs have been linked to in other pages. Avoid renaming or removing any of the divs. -->
{| class="wikitable"
{| class="wikitable"
|-  
|-  
! Term || Context || Meaning || Related Links
! scope="col" style="width:50px;" | Term
! scope="col" style="width: 60px;" | Context
! Meaning
! Related Links
|--------
|--------
|| <div id="user_environment"></div>[[User Environment]]
|| <div id="user_environment"></div>[[User Environment]]
|| Nix
|| Nix
|| A set of "active" applications. These applications usually exist in the Nix store. A single Nix user may have multiple User Environments. This is an important concept further explored in [[User Environment]]. ''Profiles'' and ''generations'' are closely related.
|| A set of "active" applications. These applications usually exist in the Nix store. A single Nix user may have multiple ''user environments''. ''Profiles'' and ''generations'' are closely related.
|| {{Nix Manual|name=Nix Manual - Basic Package Management chapter|anchor=#ch-basic-package-mgmt}} <br>{{Nix Manual|name=Nix Manual - Profiles chapter|anchor=#sec-profiles}} <br>{{Nix Manual|name=Nix Manual - nix-env|anchor=#sec-nix-env}}
|| {{Nix Manual|name=Nix Manual - Basic Package Management chapter|anchor=#ch-basic-package-mgmt}} <br>{{Nix Manual|name=Nix Manual - Profiles chapter|anchor=#sec-profiles}} <br>{{Nix Manual|name=Nix Manual - nix-env|anchor=#sec-nix-env}}
|--------
|--------
|| (User) Profile
|| (User) Profile
|| Nix
|| Nix
|| Most generally, a ''profile'' is a link to a ''generation'', and there's a '''profiles''' (note the '''s''') folder which collects types of profiles together so that they form lists of generations. In standalone Nix (e.g. on a different Linux distro), it's primary use is user profiles. In NixOS, there's also the ''system'' profile, which manages system-wide configuration (e.g. ''/etc'', the kernel, ''initrd'', ''systemd''). Tools like [[Home Manager]] also have their own profile (which would also be per-user). The user's ''active profile'' is defined in ''~/.nix-profile'', and is what all '''nix-env''' commands would operate on by default.<code>
|| Profiles simplify managing and switching between ''user environments'', and thus control which applications and system configurations are in active use. Generally, a ''profile'' is a link to a ''generation'', and the corresponding '''profiles''' folder collects a list of generations. A standalone Nix installation (i.e. on a Linux distro that is not NixOS) operates mainly on ''user'' profiles. In NixOS, there is also a ''system'' profile that manages the system-wide configuration (e.g. ''/etc'', the kernel, ''initrd'', ''systemd''). Other tools like [[Home Manager]] may also have their own profiles. By default, a user's active profile is stored at ''~/.nix-profile'':
❯ ls -l ~/.nix-profile<br>
<syntaxHighlight lang=shell>
lrwxrwxrwx 1 username users ... /home/username/.nix-profile -> /nix/var/nix/profiles/per-user/username/profile</code>
$ ls -l ~/.nix-profile
|| [http://nixos.org/nix/manual/#sec-profiles Nix Manual: Profiles]
lrwxrwxrwx ... /home/username/.nix-profile ->
/nix/var/nix/profiles/per-user/username/profile
</syntaxHighlight>
|| [http://nixos.org/nix/manual/#sec-profiles Nix Manual: Profiles]<br>[https://nixos.org/guides/nix-pills/install-on-your-running-system.html#idm140737320787760 Nix Pills - The first profile]
|--------
|--------
|| <div id="generation"></div>Generation
|| <div id="generation"></div>Generation
|| Nix
|| Nix
|| A revision of a user environment, newly created every time the system is updated (with old ones being preserved until manually removed). Technically, each generation is simply a link to a specific ''user environment'' in the Nix store. This term connotes the cloning and modification of an existing user environment. Nix's environment rollback facilities rely on Generations. The ''current generation'' is a user's currently selected ''user environment'', and is generally selected via the ''active profile'' (which is just a symlink, normally in ''/nix/var/nix/profiles/'').  
|| An instance of a ''user environment''. When a user makes any change to their environment, such as installing or removing packages, a new ''generation'' of the environment is created instead of modifying the environment in-place. This ensures that updates are atomic and the user can easily roll-back to any previous generation if something goes wrong. The ''current generation'' is a user's currently active user profile.
|| [http://nixos.org/nix/manual/#sec-profiles Nix Manual: Profiles]
|| [https://nix.dev/manual/nix/stable/package-management/profiles Nix Manual: Profiles]
|--------
|--------
|| Derivation
|| Derivation
|| Nix
|| Nix
|| A Nix expression which describes a build action. When evaluated, it creates one or more entries in the Nix Store. The <code>nix-instantiate</code> command is the command which creates entries in the Nix Store, while the <code>nix-env</code> and <code>nix-build</code> commands are its user-friendly interface.
|| A Nix expression which describes a build action. Derivations are analogous to package definitions in other package managers. High-level derivations, such as the ones describing packages in [[Nixpkgs]], get evaluated into low-level derivations (called ''store derivations''), for instance by using the <code>nix-instantiate</code> command. <code>nix-store --realise</code> runs the build commands described in the low-level derivation, producing one or more ''output paths''. <code>nix-build</code> is a user-friendly wrapper for the previous two commands.
|| [http://nixos.org/nix/manual/#gloss-derivation Nix Manual: Glossary -> Derivation] <br> [http://nixos.org/nix/manual/#ssec-derivation Nix Manual: Derivation]
|| [http://nixos.org/nix/manual/#gloss-derivation Nix Manual: Glossary - Derivation] <br> [http://nixos.org/nix/manual/#ssec-derivation Nix Manual: Derivation]
|--------
|| Output path
|| Nix
|| A ''store path'' produced by a derivation. These are generally analogous to built packages, or pieces of them.
<syntaxHighlight lang=shell>
$ ls -ld /nix/store/*-firefox-9*/
dr-xr-xr-x ... /nix/store/v4b8...3d0w-firefox-92.0/
</syntaxHighlight>
|| [http://nixos.org/nix/manual/#ssec-derivation Nix Manual: Derivation]
|--------
|--------
|| <code>rec { }</code>
|| <code>rec { }</code>
|| Nix expressions
|| Nix expressions
|| The <code>{ }</code> block contains "mutually recursive" attributes, which means they can refer to each other.
|| The <code>{ }</code> block contains "mutually recursive" attributes, which means they can refer to each other.
|| [http://nixos.org/nix/manual/#ex-hello-composition Composing the Hello Package]
|| [https://nix.dev/manual/nix/2.24/language/syntax.html#recursive-sets Nix Manual: Syntax and semantics: Recursive sets]
|--------
|--------
|| <code>expression evaluator</code>
|| <code>expression evaluator</code>
Line 53: Line 69:
|--------
|--------
|| attribute path
|| attribute path
|| nix-env takes this if you pass the `-A` flag [http://nixos.org/nix/manual/#opt-attr]  
|| nix-env takes this if you pass the `-A` flag [http://nixos.org/nix/manual/#opt-attr]
|| an unambiguous identifier for a package
|| an unambiguous identifier for a package
||  
||  
Line 69: Line 85:
|| selection path
|| selection path
|| nix-shell error message [https://github.com/NixOS/nix/blob/bdc4a0b54d54146448061dd9a248212f98a9f801/src/libexpr/attr-path.cc#L73]
|| nix-shell error message [https://github.com/NixOS/nix/blob/bdc4a0b54d54146448061dd9a248212f98a9f801/src/libexpr/attr-path.cc#L73]
|| see "attribute path"[http://nixos.org/irc/logs/log.20151103]  
|| see "attribute path"[http://nixos.org/irc/logs/log.20151103]
||  
||  
|--------
|--------
Line 94: Line 110:
-->
-->
|}
|}
 
</translate>
{{Bottom whitespace}}
Retrieved from "https://wiki.nixos.org/wiki/Terms_and_Definitions_in_Nix_Project"