Documentation Gaps: Difference between revisions

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And an explanation of what they do and what they are used for.

== How do manpages work? Or: <code>environment.pathsToLink</code> and <code>buildEnv</code> ==

I'm trying to understand how manpages work in Nix/NixOS.

There is a pacakge called [https://github.com/NixOS/nixpkgs/blob/master/pkgs/tools/misc/man-db/default.nix#L29 <code>man-db</code>], which seems to be looking in <code>/nix/var/nix/profiles/default/share/man</code> for manpages. It can build a cache at <code>/var/cache/man/nixpkgs</code>.

Under NixOS (on my machine, running NixOS 20.09), these paths do not exist. <code>man-db</code> is installed as a NixOS module, the configuration is at [https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/misc/documentation.nix#L104 <code>nixos/modules/misc/documentation.nix</code>] in the nixpkgs repository. Manpages are in <code>/run/current-system/sw/share/man</code>, and the cache resides in <code>/var/cache/man/nixos</code>.

What I don't understand is: How are these paths populated? In the module, if <code>man</code> is enabled, <code>environment.pathsToLink</code> is set to <code>[ "/share/man" ]</code>. The documentation describes this option as "List of directories to be symlinked in /run/current-system/sw". Does this mean that for every package in <code>environment.systemPackages</code>, it does something like <code>for f in ${pkg}/share/man/* ; do ln -s $f /run/current-system/sw/share/man/$fname ; done</code>? I could only find that <code>environment.systemPackages</code> is later used to make a <code>buildEnv</code>, but what <code>buildEnv</code> does is a mystery to me.

So, to summarize my ramblings, I guess I would find a thorough documentation of buildEnv very helpful.

@@ Line 55: / Line 55: @@
 And an explanation of what they do and what they are used for.
+== How do manpages work? Or: <code>environment.pathsToLink</code> and <code>buildEnv</code> ==
+I'm trying to understand how manpages work in Nix/NixOS.
+There is a pacakge called [https://github.com/NixOS/nixpkgs/blob/master/pkgs/tools/misc/man-db/default.nix#L29 <code>man-db</code>], which seems to be looking in <code>/nix/var/nix/profiles/default/share/man</code> for manpages. It can build a cache at <code>/var/cache/man/nixpkgs</code>.
+Under NixOS (on my machine, running NixOS 20.09), these paths do not exist. <code>man-db</code> is installed as a NixOS module, the configuration is at [https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/misc/documentation.nix#L104 <code>nixos/modules/misc/documentation.nix</code>] in the nixpkgs repository. Manpages are in <code>/run/current-system/sw/share/man</code>, and the cache resides in <code>/var/cache/man/nixos</code>.
+What I don't understand is: How are these paths populated? In the module, if <code>man</code> is enabled, <code>environment.pathsToLink</code> is set to <code>[ "/share/man" ]</code>. The documentation describes this option as "List of directories to be symlinked in /run/current-system/sw". Does this mean that for every package in <code>environment.systemPackages</code>, it does something like <code>for f in ${pkg}/share/man/* ; do ln -s $f /run/current-system/sw/share/man/$fname ; done</code>? I could only find that <code>environment.systemPackages</code> is later used to make a <code>buildEnv</code>, but what <code>buildEnv</code> does is a mystery to me.
+So, to summarize my ramblings, I guess I would find a thorough documentation of buildEnv very helpful.