pkg-config does not know any libraries.

[kindaro]

Issue description

I need to have some libraries, such as libsystemd, available and visible with pkg-config to do my programming. Unfortunately, I discover that pkg-config --list-all output is completely blank. I can fix it by an appropriate assignment of PKG_CONFIG_PATH, but I would expect it to work out of the box.

Steps to reproduce

Install Nix and then install systemd and pkg-config via nix-env.

% pkg-config --modversion libsystemd
Package libsystemd was not found in the pkg-config search path.
Perhaps you should add the directory containing `libsystemd.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libsystemd' found
% export PKG_CONFIG_PATH=$(dirname `find /nix -name 'libsystemd.pc'`)
% pkg-config --modversion libsystemd
242

Technical details

% nix-shell -p nix-info --run "nix-info -m"
warning: Nix search path entry '/nix/var/nix/profiles/per-user/root/channels/nixpkgs' does not exist, ignoring
warning: Nix search path entry '/nix/var/nix/profiles/per-user/root/channels/nixpkgs' does not exist, ignoring
 - system: `"x86_64-linux"`
 - host os: `Linux 5.1.16-arch1-1-ARCH, Arch Linux, noversion`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.2.2`
 - channels(kindaro): `"nixpkgs-19.09pre184803.d567c486ca5"`
warning: Nix search path entry '/nix/var/nix/profiles/per-user/root/channels/nixpkgs' does not exist, ignoring
 - nixpkgs: `/home/kindaro/.nix-defexpr/channels/nixpkgs`

[matthewbauer]

Nixpkgs does not install headers and pkgconfig meta by default - only runtime dependencies are made available in $HOME/.nix-profile. If you need a development environment like you would get in a Nix builder, you can use nix-shell:

$ nix-shell -p systemd pkgconfig --run 'echo $PKG_CONFIG_PATH'

[colemickens]

@matthewbauer Is this documented? I was just scrolling through issues and saw this. The distinction between nix-env and nix-shell is subtle but rather important, especially for new nixos users...

[lheckemann]

https://nixos.wiki/wiki/FAQ/Libraries

[stale[bot]]

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[andreykaipov]

Just ran into this. Thought I was going crazy. Figured it must be something Nix is doing so I went searching for issues. I don't know if it's possible, but maybe nix-env can output a warning and link to https://nixos.wiki/wiki/FAQ/Libraries when a user tries to install libraries?

Related issue: https://github.com/NixOS/nixpkgs/issues/41825.

[stale[bot]]

I marked this as stale due to inactivity. → More info

[tv42]

The command from https://github.com/NixOS/nixpkgs/issues/64530#issuecomment-509695590 does not set PKG_CONFIG_PATH:

$ nix-shell -p systemd pkgconfig --run 'echo $PKG_CONFIG_PATH'

[lheckemann]

@tv42 it now sets PKG_CONFIG_PATH_FOR_TARGET as part of improved cross-compilation support. Nonetheless, pkg-config works correctly:

$ nix-shell -p systemd pkgconfig --run 'pkg-config --libs libsystemd'
-L/nix/store/zc9r3iin18bccr3sjgwsgd6snp8g9g27-systemd-249.7/lib -lsystemd

[chris-martin]

It doesn't seem like pkg-config is picking up anything?

$ nix shell nixpkgs#systemd nixpkgs#pkgconfig nixpkgs#zlib -c pkg-config --list-all
[ no output ]

[tv42]

Seems to be a difference between nix-shell and nix shell:

$ nix-shell -p systemd pkgconfig --run 'pkg-config --libs libsystemd'
-L/nix/store/cfqfzy5k6l7b2f3bxy2zdhp9sjiw8ijd-systemd-249.5/lib -lsystemd
$ nix shell nixpkgs#systemd nixpkgs#pkgconfig -c pkg-config --libs libsystemd
Package libsystemd was not found in the pkg-config search path.
Perhaps you should add the directory containing `libsystemd.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libsystemd' found

[Lord-Valen]

It doesn't seem like pkg-config is picking up anything?

$ nix shell nixpkgs#systemd nixpkgs#pkgconfig nixpkgs#zlib -c pkg-config --list-all
[ no output ]

Seems to be a difference between nix-shell and nix shell:

$ nix-shell -p systemd pkgconfig --run 'pkg-config --libs libsystemd'
-L/nix/store/cfqfzy5k6l7b2f3bxy2zdhp9sjiw8ijd-systemd-249.5/lib -lsystemd
$ nix shell nixpkgs#systemd nixpkgs#pkgconfig -c pkg-config --libs libsystemd
Package libsystemd was not found in the pkg-config search path.
Perhaps you should add the directory containing `libsystemd.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libsystemd' found

It seems to me that this should be another issue (possibly a nix issue?), since this issue is concerned with documenting pkg-config behaviour (or lackthereof) in nix-env and nix-shell, not nix-shell andnix shell. Curious behaviour, though. The same problem occurs with nix develop.

Seems numtide devshells remove a lot of the usual hooks which would ordinarily handle this. It probably works with the normal mkShell. Speaking of which... https://discourse.nixos.org/t/flakes-how-to-make-pkg-config-work-with-nix-shell/16305/2

[tv42]

It seems documenting "it does not work" is much less useful than making it work, though. And nix shell/nix develop is the future, isn't it? Probably more bang for buck fixing it there.

[PierreR]

"It does not work" and that is not an issue, is that it ?

[DUOLabs333]

I just ran into this problem --- is there a way to just add the proper setup hooks to your profile.nix/home.nix directly (I don't use nix-shell)?