Terms and Definitions in Nix Project: Difference between revisions

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|| <div id="generation"></div>Generation

|| 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]

|--------

|| Derivation

|| Nix

|| A Nix expression which describes a build action. High-level derivations (~~like~~ the ones describing packages in [[Nixpkgs]]), get evaluated into low-level derivations (called ''store derivations'' ~~— because they wind up in~~ the ~~''Nix store'').~~ <code>nix-instantiate</code> ~~is the~~ command ~~which translates high-level derivations into low-level ones~~. <code>nix-store --realise</code> ~~can then check and finish their~~ build ~~for~~ the ~~''nix store''~~, producing ''output ~~path(s)~~''. <code>nix-build</code> is a user-friendly wrapper for the previous commands~~. Derivations are analogous to package definitions in other package managers~~.

|| 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> run the build commands described in the 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]

|--------

|| Output path

|| Nix

|| A ''store path'' produced by a derivation. These are generally analogous to built packages, or pieces of them.~~<br>~~<syntaxHighlight lang=shell>❯ ls -ld /nix/store/*-firefox-9*/

|| A ''store path'' produced by a derivation. These are generally analogous to built packages, or pieces of them.

dr-xr-xr-x ... /nix/store/v4b8...3d0w-firefox-92.0/</syntaxHighlight>

$ 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]

|--------

@@ Line 26: / Line 26: @@
 || <div id="generation"></div>Generation
 || 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]
 |--------
 || Derivation
 || Nix
-|| A Nix expression which describes a build action. High-level derivations (like the ones describing packages in [[Nixpkgs]]), get evaluated into low-level derivations (called ''store derivations'' &mdash; because they wind up in the ''Nix store''). <code>nix-instantiate</code> is the command which translates high-level derivations into low-level ones. <code>nix-store --realise</code> can then check and finish their build for the ''nix store'', producing ''output path(s)''. <code>nix-build</code> is a user-friendly wrapper for the previous commands. Derivations are analogous to package definitions in other package managers.
+|| 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> run the build commands described in the 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]
 |--------
 || Output path
 || Nix
-|| A ''store path'' produced by a derivation. These are generally analogous to built packages, or pieces of them.<br><syntaxHighlight lang=shell>❯ ls -ld /nix/store/*-firefox-9*/
+|| A ''store path'' produced by a derivation. These are generally analogous to built packages, or pieces of them.
-dr-xr-xr-x ... /nix/store/v4b8...3d0w-firefox-92.0/</syntaxHighlight>
+<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]
 |--------