nixos/nixos-enter: hide systemd-tmpfiles errors

Due to missing `/etc/machine-id` in the new root, systemd-tmpfiles
outputs a bunch of scary warnings like "Failed to replace specifiers in
'/run/log/journal/%m'". We only care about /tmp, so hide them.

`-E` is an alias for `--exclude-prefix=/dev --exclude-prefix=/proc
--exclude-prefix=/run --exclude-prefix=/sys`.

1 files changed, 3 insertions, 2 deletions

diff --git a/nixos/modules/installer/tools/nixos-enter.sh b/nixos/modules/installer/tools/nixos-enter.sh
index 30113ee0050..60a86d89abb 100644..100755
--- a/nixos/modules/installer/tools/nixos-enter.sh
+++ b/nixos/modules/installer/tools/nixos-enter.sh
@@ -100,8 +100,9 @@ chroot_add_resolv_conf "$mountPoint" || echo "$0: failed to set up resolv.conf"
     # Run the activation script. Set $LOCALE_ARCHIVE to supress some Perl locale warnings.
     LOCALE_ARCHIVE="$system/sw/lib/locale/locale-archive" IN_NIXOS_ENTER=1 chroot "$mountPoint" "$system/activate" 1>&2 || true
 
-    # Create /tmp
-    chroot "$mountPoint" "$system/sw/bin/systemd-tmpfiles" --create --remove --exclude-prefix=/dev 1>&2 || true
+    # Create /tmp. This is needed for nix-build and the NixOS activation script to work.
+    # Hide the unhelpful "failed to replace specifiers" errors caused by missing /etc/machine-id.
+    chroot "$mountPoint" "$system/sw/bin/systemd-tmpfiles" --create --remove -E 2> /dev/null || true
 )
 
 unset TMPDIR