Merge pull request #11433 from abathur/fix_sequoia_migration_gid

use existing GID in sequoia migration script

scripts/sequoia-nixbld-user-migration.sh

@@ -17,18 +17,23 @@ any_nixbld(){
  dscl . list /Users UniqueID | grep -E '\b_nixbld' >/dev/null
 }
 
+dsclattr() {
+ dscl . -read "$1" | awk "/$2/ { print \$2 }"
+}
+
 re_create_nixbld_user(){
  local name uid
 
  name="$1"
  uid="$2"
+ gid="$3"
 
  sudo /usr/bin/dscl . -create "/Users/$name" "UniqueID" "$uid"
  sudo /usr/bin/dscl . -create "/Users/$name" "IsHidden" "1"
  sudo /usr/bin/dscl . -create "/Users/$name" "NFSHomeDirectory" "/var/empty"
  sudo /usr/bin/dscl . -create "/Users/$name" "RealName" "Nix build user $name"
  sudo /usr/bin/dscl . -create "/Users/$name" "UserShell" "/sbin/nologin"
- sudo /usr/bin/dscl . -create "/Users/$name" "PrimaryGroupID" "30001"
+ sudo /usr/bin/dscl . -create "/Users/$name" "PrimaryGroupID" "$gid"
 }
 
 hit_id_cap(){
@@ -68,11 +73,12 @@ temporarily_move_existing_nixbld_uids(){
 }
 
 change_nixbld_uids(){
- local name next_id user_n
+ local existing_gid name next_id user_n
 
  ((next_id=NEW_NIX_FIRST_BUILD_UID))
  ((user_n=1))
  name="$(nix_user_n "$user_n")"
+ existing_gid="$(dsclattr "/Groups/nixbld" "PrimaryGroupID")"
 
  # we know that we have *some* nixbld users, but macOS may have
  # already clobbered the first few users if this system has been
@@ -91,7 +97,7 @@ change_nixbld_uids(){
  fi
  done
 
- re_create_nixbld_user "$name" "$next_id"
+ re_create_nixbld_user "$name" "$next_id" "$existing_gid"
  echo " $name was missing; created with uid: $next_id"
 
  ((user_n++))