From 101105ebe93ac98d881dc9b46443a147b5390514 Mon Sep 17 00:00:00 2001
From: Giulio Eulisse <10544+ktf@users.noreply.github.com>
Date: Sat, 7 Nov 2026 14:20:55 +0100
Subject: [PATCH] FST: measure the AO2D size portably

stat -c%s is GNU syntax; BSD stat, as on macOS, rejects it, so the ASYNC
check read an empty size and failed with "AO2D file (AO2D.root) exists
but is empty" on a 470 kB AO2D. wc -c works on both.
---
 prodtests/full_system_test.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/prodtests/full_system_test.sh b/prodtests/full_system_test.sh
index c0195adb1bcc9..593bd56a366d3 100755
--- a/prodtests/full_system_test.sh
+++ b/prodtests/full_system_test.sh
@@ -337,7 +337,7 @@ for STAGE in $STAGES; do
    # Check AOD production for ASYNC stage
   if [[ "$STAGE" = "ASYNC" ]]; then
     if [[ -f "AO2D.root" ]]; then
-      aod_size=`stat -c%s AO2D.root`
+      aod_size=$(wc -c < AO2D.root)
       if [[ $aod_size -gt 0 ]]; then
         echo "AO2D file produced: AO2D.root (size: ${aod_size} bytes)"
         echo "aod_size_${STAGE},${TAG} value=${aod_size}" >> ${METRICFILE}