substituteStream warning during nixos-rebuild

mkg · October 2, 2021, 7:07pm

Rebuilding configuration.nix gives many warnings of the form:

substituteStream(): WARNING: pattern <pat> doesn't match anything in file <pat>

where <pat> is one of /bin/mount, /sbin;/blkid, /sbin/mdadm, /sbin/modprobe, /usr/bin/basename, and /usr/bin/readlink and all of the <files> are from udev-rules. I believe it started happening after upgrading to 21.05 (or maybe 20.09). The warnings appear to be innocuous. Why does the warning exist and shouldn’t it removed?

jtojnar · October 2, 2021, 7:37pm

They come from fixing the paths in udev rule files – not all files contain all of these paths so you get the warning:

github.com

NixOS/nixpkgs/blob/faf57c8e3a35eaf155fa2c7dcfeb7a0ed2fb3f57/nixos/modules/services/hardware/udev.nix#L55-L64


      
          # Fix some paths in the standard udev rules.  Hacky.
          for i in $out/*.rules; do
            substituteInPlace $i \
              --replace \"/sbin/modprobe \"${pkgs.kmod}/bin/modprobe \
              --replace \"/sbin/mdadm \"${pkgs.mdadm}/sbin/mdadm \
              --replace \"/sbin/blkid \"${pkgs.util-linux}/sbin/blkid \
              --replace \"/bin/mount \"${pkgs.util-linux}/bin/mount \
              --replace /usr/bin/readlink ${pkgs.coreutils}/bin/readlink \
              --replace /usr/bin/basename ${pkgs.coreutils}/bin/basename
          done

qm3ster · November 6, 2022, 1:29pm

I understand why they happen, but shouldn’t we suppress them?