Close each discovered queue before inspecting or removing it

Checking a queue for jobs and then deleting it leaves a window in between, and the sudo that does the deleting can sit at a password prompt for as long as someone takes to type. A job submitted in that window was cancelled by a deletion that had already decided the queue was empty. cupsreject closes the queue to new work first, which also stops more jobs piling onto one that is being left behind and can no longer route them. It comes from the cups package, which stays.

What a queue with jobs on it means is now said rather than implied: whatever is already at the printer finishes, whatever is still waiting cannot be routed with the daemon gone, and the person who owns them has to cancel what is left.

A queue that another administrator removed while this was running is the outcome wanted, not a failure to keep the package installed for, so a deletion that fails is checked against whether the destination is still there.

Co-Authored-By: Codex XHigh <noreply@openai.com>

migrations/1788009111.sh

@@ -81,15 +81,28 @@ while IFS= read -r queue; do
     continue
   fi
 
-  # Removing a queue aborts what is printing on it. The implicitclass backend
-  # only needs cups-browsed to pick a destination, so a job already past that
-  # point finishes on its own even though the daemon has stopped -- and a job
-  # that has not is one this cannot route anyway. Either way the queue is left
-  # for the person whose job it is, and named so they know to remove it.
+  # Close the queue to new jobs before looking at what is on it. Otherwise a job
+  # submitted between the check and the removal -- the sudo below can sit at a
+  # password prompt for as long as someone takes to type it -- is cancelled by a
+  # deletion that decided the queue was empty. It also stops more jobs piling
+  # onto a queue that is being left behind and can no longer route them.
+  if ! sudo cupsreject -r "Printer discovery has been removed from Omarchy" "$queue"; then
+    echo "  Could not stop $queue accepting new jobs, so it is being left alone."
+    unremoved=1
+    continue
+  fi
+
+  # Removing a queue cancels the jobs on it. implicitclass needs cups-browsed
+  # only to pick a destination, so a job already past that point finishes on its
+  # own; one still waiting cannot, because the daemon that would route it has
+  # stopped. Neither is this migration's to throw away, so the queue is left for
+  # whoever owns them, and what will and will not happen is said rather than
+  # implied.
   if job_report=$(LC_ALL=C lpstat -o "$queue" 2>/dev/null); then
     if [[ -n $job_report ]]; then
-      echo "  $queue still has jobs, so it is being left alone."
-      echo "  Once they finish or are cancelled, remove it in Print Settings; it cannot print again."
+      echo "  $queue still has jobs and is no longer taking new ones, so it is being left alone."
+      echo "  Anything already sent to the printer finishes; anything still waiting cannot be routed now."
+      echo "  Cancel what is left and remove the queue in Print Settings."
       continue
     fi
   else
@@ -97,9 +110,14 @@ while IFS= read -r queue; do
     continue
   fi
 
+  # A queue another administrator removed while this was running is a queue that
+  # is gone, which is the outcome wanted -- not a failure worth keeping the
+  # package for.
   if ! sudo lpadmin -x "$queue"; then
-    echo "  Could not remove the queue $queue."
-    unremoved=1
+    if LC_ALL=C lpstat -p "$queue" >/dev/null 2>&1; then
+      echo "  Could not remove the queue $queue."
+      unremoved=1
+    fi
   fi
 done <<<"$generated_queues"