diff --git a/fs_mgr/tests/adb-remount-test.sh b/fs_mgr/tests/adb-remount-test.sh
index 11e4790..e5f6ecb 100755
--- a/fs_mgr/tests/adb-remount-test.sh
+++ b/fs_mgr/tests/adb-remount-test.sh
@@ -241,15 +241,15 @@
   if [ X"${duration}" != X"${duration%s}" ]; then
     duration=${duration%s}
   elif [ X"${duration}" != X"${duration%m}" ]; then
-    duration=`expr ${duration%m} \* 60`
+    duration=$(( ${duration%m} * 60 ))
   elif [ X"${duration}" != X"${duration%h}" ]; then
-    duration=`expr ${duration%h} \* 3600`
+    duration=$(( ${duration%h} * 3600 ))
   elif [ X"${duration}" != X"${duration%d}" ]; then
-    duration=`expr ${duration%d} \* 86400`
+    duration=$(( ${duration%d} * 86400 ))
   fi
-  local seconds=`expr ${duration} % 60`
-  local minutes=`expr \( ${duration} / 60 \) % 60`
-  local hours=`expr ${duration} / 3600`
+  local seconds=$(( ${duration} % 60 ))
+  local minutes=$(( ( ${duration} / 60 ) % 60 ))
+  local hours=$(( ${duration} / 3600 ))
   if [ 0 -eq ${minutes} -a 0 -eq ${hours} ]; then
     if [ 1 -eq ${duration} ]; then
       echo 1 second
@@ -265,10 +265,10 @@
     return
   fi
   if [ 0 -eq ${hours} ]; then
-    echo ${minutes}:`expr ${seconds} / 10``expr ${seconds} % 10`
+    echo ${minutes}:$(( ${seconds} / 10 ))$(( ${seconds} % 10 ))
     return
   fi
-  echo ${hours}:`expr ${minutes} / 10``expr ${minutes} % 10`:`expr ${seconds} / 10``expr ${seconds} % 10`
+  echo ${hours}:$(( ${minutes} / 10 ))$(( ${minutes} % 10 )):$(( ${seconds} / 10 ))$(( ${seconds} % 10))
 }
 
 [ "USAGE: USB_DEVICE=\`usb_devnum [--next]\`
@@ -282,7 +282,7 @@
     if [ -n "${usb_device}" ]; then
       USB_DEVICE=dev${usb_device}
     elif [ -n "${USB_DEVICE}" -a "${1}" ]; then
-      USB_DEVICE=dev`expr ${USB_DEVICE#dev} + 1`
+      USB_DEVICE=dev$(( ${USB_DEVICE#dev} + 1 ))
     fi
     echo "${USB_DEVICE}"
   fi
@@ -298,10 +298,10 @@
   if [ -n "${1}" -a -n "`which timeout`" ]; then
     USB_DEVICE=`usb_devnum --next`
     duration=`format_duration ${1}`
-    echo -n ". . . waiting ${duration}" ${ANDROID_SERIAL} ${USB_ADDRESS} ${USB_DEVICE} "${CR}"
+    echo -n ". . . waiting ${duration}" ${ANDROID_SERIAL} ${USB_ADDRESS} ${USB_DEVICE} "${CR}" >&2
     timeout --preserve-status --signal=KILL ${1} adb wait-for-device 2>/dev/null
     ret=${?}
-    echo -n "                                                                             ${CR}"
+    echo -n "                                                                             ${CR}" >&2
   else
     adb wait-for-device
     ret=${?}
@@ -314,7 +314,7 @@
     fi
   fi
   local end=`date +%s`
-  local diff_time=`expr ${end} - ${start}`
+  local diff_time=$(( ${end} - ${start} ))
   local _print_time=${print_time}
   if [ ${diff_time} -lt 15 ]; then
     _print_time=false
@@ -494,7 +494,7 @@
         break
       fi
     fi
-    counter=`expr ${counter} + 1`
+    counter=$(( ${counter} + 1 ))
     if [ ${counter} -gt ${timeout} ]; then
       ${exit_function}
       echo "ERROR: wait_for_screen() timed out (`format_duration ${timeout}`)" >&2
@@ -596,7 +596,7 @@
     echo "${BLUE}[     INFO ]${NORMAL} end `date`"
     [ -n "${start_time}" ] || return
     end_time=`date +%s`
-    local diff_time=`expr ${end_time} - ${start_time}`
+    local diff_time=$(( ${end_time} - ${start_time} ))
     echo "${BLUE}[     INFO ]${NORMAL} duration `format_duration ${diff_time}`"
   fi >&2
 }
@@ -874,9 +874,6 @@
   NORMAL=""
 fi
 
-# Set an ERR trap handler to report any unhandled error
-trap 'die "line ${LINENO}: unhandled error"' ERR
-
 if ${print_time}; then
   echo "${BLUE}[     INFO ]${NORMAL}" start `date` >&2
 fi
@@ -964,7 +961,7 @@
         ;;
     esac
     size=`adb_su cat /sys/block/${device}/size 2>/dev/null </dev/null` &&
-      size=`expr ${size} / 2` &&
+      size=$(( ${size} / 2 )) &&
       echo "${BLUE}[     INFO ]${NORMAL} partition ${name} device ${device} size ${size}K" >&2
   done
 
@@ -1097,8 +1094,9 @@
 D=`adb_sh df -k </dev/null` &&
   H=`echo "${D}" | head -1` &&
   D=`echo "${D}" | grep -v " /vendor/..*$" | grep "^overlay "` &&
-  echo "${H}" &&
-  echo "${D}" &&
+  ( echo "${H}" &&
+    echo "${D}"
+  ) >&2 &&
   die "overlay takeover unexpected at this phase"
 echo "${GREEN}[       OK ]${NORMAL} no overlay present before setup" >&2
 overlayfs_needed=true
@@ -1117,7 +1115,7 @@
 done
 D=`adb_sh df -k ${D} </dev/null |
    sed 's@\([%] /\)\(apex\|bionic\|system\|vendor\)/[^ ][^ ]*$@\1@'`
-echo "${D}"
+echo "${D}" >&2
 if [ X"${D}" = X"${D##* 100[%] }" ] && ${no_dedupe} ; then
   overlayfs_needed=false
   # if device does not need overlays, then adb enable-verity will brick device
@@ -1139,7 +1137,7 @@
 T=$(adb_date)
 H=$(adb_su disable-verity -R 2>&1)
 err="${?}"
-echo "${H}"
+echo "${H}" >&2
 
 if [ "${err}" != 0 ]; then
   die -t "${T}" "disable-verity -R"
@@ -1176,15 +1174,15 @@
 
 D=`adb remount 2>&1`
 ret=${?}
-echo "${D}"
+echo "${D}" >&2
 [ ${ret} != 0 ] ||
   [ X"${D}" = X"${D##*remount failed}" ] ||
-  ( [ -n "${L}" ] && echo "${L}" && false ) ||
+  ( [ -n "${L}" ] && echo "${L}" && false ) >&2 ||
   die -t "${T}" "adb remount failed"
 D=`adb_sh df -k </dev/null` &&
   H=`echo "${D}" | head -1` &&
   D=`echo "${D}" | skip_unrelated_mounts | grep "^overlay "` ||
-  ( [ -n "${L}" ] && echo "${L}" && false )
+  ( [ -n "${L}" ] && echo "${L}" && false ) >&2
 ret=${?}
 uses_dynamic_scratch=false
 scratch_partition=
@@ -1204,7 +1202,7 @@
   M=`adb_sh cat /proc/mounts </dev/null |
      sed -n 's@\([^ ]*\) /mnt/scratch \([^ ]*\) .*@\2 on \1@p'`
   [ -n "${M}" ] &&
-    echo "${BLUE}[     INFO ]${NORMAL} scratch filesystem ${M}"
+    echo "${BLUE}[     INFO ]${NORMAL} scratch filesystem ${M}" >&2
   uses_dynamic_scratch=true
   if [ "${M}" != "${M##*/dev/block/by-name/}" ]; then
     uses_dynamic_scratch=false
@@ -1225,8 +1223,9 @@
     fi
   done
 
-  echo "${H}" &&
-    echo "${D}" &&
+  ( echo "${H}" &&
+    echo "${D}"
+  ) >&2 &&
     echo "${D}" | grep "^overlay .* /system\$" >/dev/null ||
     die  "overlay takeover after remount"
   !(adb_sh grep "^overlay " /proc/mounts </dev/null |
@@ -1261,7 +1260,7 @@
     D=`adb_sh df -k ${D} </dev/null |
        sed -e 's@\([%] /\)\(apex\|bionic\|system\|vendor\)/[^ ][^ ]*$@\1@' \
            -e 's/^Filesystem      /Filesystem (rw) /'`
-  [ -z "${D}" ] || echo "${D}"
+  [ -z "${D}" ] || echo "${D}" >&2
   ${bad_rw} && die "remount overlayfs missed a spot (rw)"
 else
   if [ ${ret} = 0 ]; then
@@ -1323,7 +1322,7 @@
   D=`adb_su df -k </dev/null` &&
     H=`echo "${D}" | head -1` &&
     D=`echo "${D}" | grep -v " /vendor/..*$" | grep "^overlay "` ||
-    ( echo "${L}" && false ) ||
+    ( echo "${L}" && false ) >&2 ||
     die -d "overlay takeover failed after reboot"
 
   adb_su sed -n '1,/overlay \/system/p' /proc/mounts </dev/null |
@@ -1385,20 +1384,20 @@
 is_userspace_fastboot=false
 
 if ! ${is_bootloader_fastboot}; then
-  echo "${YELLOW}[  WARNING ]${NORMAL} does not support fastboot, skipping"
+  echo "${YELLOW}[  WARNING ]${NORMAL} does not support fastboot, skipping" >&2
 elif [ -z "${ANDROID_PRODUCT_OUT}" ]; then
-  echo "${YELLOW}[  WARNING ]${NORMAL} build tree not setup, skipping"
+  echo "${YELLOW}[  WARNING ]${NORMAL} build tree not setup, skipping" >&2
 elif [ ! -s "${ANDROID_PRODUCT_OUT}/vendor.img" ]; then
-  echo "${YELLOW}[  WARNING ]${NORMAL} vendor image missing, skipping"
+  echo "${YELLOW}[  WARNING ]${NORMAL} vendor image missing, skipping" >&2
 elif [ "${ANDROID_PRODUCT_OUT}" = "${ANDROID_PRODUCT_OUT%*/${H}}" ]; then
-  echo "${YELLOW}[  WARNING ]${NORMAL} wrong vendor image, skipping"
+  echo "${YELLOW}[  WARNING ]${NORMAL} wrong vendor image, skipping" >&2
 elif [ -z "${ANDROID_HOST_OUT}" ]; then
-  echo "${YELLOW}[  WARNING ]${NORMAL} please run lunch, skipping"
+  echo "${YELLOW}[  WARNING ]${NORMAL} please run lunch, skipping" >&2
 elif ! (
           adb_cat /vendor/build.prop |
           cmp -s ${ANDROID_PRODUCT_OUT}/vendor/build.prop
        ) >/dev/null 2>/dev/null; then
-  echo "${YELLOW}[  WARNING ]${NORMAL} vendor image signature mismatch, skipping"
+  echo "${YELLOW}[  WARNING ]${NORMAL} vendor image signature mismatch, skipping" >&2
 else
   wait_for_screen
   avc_check
@@ -1412,7 +1411,7 @@
     die "fastboot flash vendor"
   fastboot_getvar is-userspace yes &&
     is_userspace_fastboot=true
-  if [ -n "${scratch_paritition}" ]; then
+  if [ -n "${scratch_partition}" ]; then
     fastboot_getvar partition-type:${scratch_partition} raw ||
       ( fastboot reboot && false) ||
       die "fastboot can not see ${scratch_partition} parameters"
@@ -1444,7 +1443,7 @@
   fi
   fastboot reboot ||
     die "can not reboot out of fastboot"
-  echo "${YELLOW}[  WARNING ]${NORMAL} adb after fastboot"
+  echo "${YELLOW}[  WARNING ]${NORMAL} adb after fastboot" >&2
   adb_wait ${ADB_WAIT} ||
     fixup_from_recovery ||
     die "did not reboot after formatting ${scratch_partition} `usb_status`"
@@ -1453,8 +1452,9 @@
       D=`adb_sh df -k </dev/null` &&
       H=`echo "${D}" | head -1` &&
       D=`echo "${D}" | skip_unrelated_mounts | grep "^overlay "` &&
-      echo "${H}" &&
-      echo "${D}" &&
+      ( echo "${H}" &&
+        echo "${D}"
+      ) >&2 &&
       echo "${D}" | grep "^overlay .* /system\$" >/dev/null ||
       die  "overlay /system takeover after flash vendor"
     echo "${D}" | grep "^overlay .* /vendor\$" >/dev/null &&
@@ -1498,7 +1498,7 @@
 L=
 D="${H%?Now reboot your device for settings to take effect*}"
 if [ X"${H}" != X"${D}" ]; then
-  echo "${YELLOW}[  WARNING ]${NORMAL} adb remount requires a reboot after partial flash (legacy avb)"
+  echo "${YELLOW}[  WARNING ]${NORMAL} adb remount requires a reboot after partial flash (legacy avb)" >&2
   L=`adb_logcat -b all -v nsec -t ${T} 2>&1`
   adb_reboot &&
     adb_wait ${ADB_WAIT} &&
@@ -1508,11 +1508,11 @@
   H=`adb remount 2>&1`
   err=${?}
 fi
-echo "${H}"
+echo "${H}" >&2
 [ ${err} = 0 ] &&
   ( adb_sh rm /vendor/hello </dev/null 2>/dev/null || true ) &&
   adb_sh rm /system/hello /system/priv-app/hello </dev/null ||
-  ( [ -n "${L}" ] && echo "${L}" && false ) ||
+  ( [ -n "${L}" ] && echo "${L}" && false ) >&2 ||
   die -t ${T} "cleanup hello"
 B="`adb_cat /system/hello`"
 check_eq "cat: /system/hello: No such file or directory" "${B}" after rm
@@ -1556,7 +1556,7 @@
   err=${?}
   if [ X"${D}" != "${D%?Now reboot your device for settings to take effect*}" ]
   then
-    echo "${YELLOW}[  WARNING ]${NORMAL} adb disable-verity requires a reboot after partial flash"
+    echo "${YELLOW}[  WARNING ]${NORMAL} adb disable-verity requires a reboot after partial flash" >&2
     adb_reboot &&
       adb_wait ${ADB_WAIT} &&
       adb_root ||
@@ -1567,7 +1567,7 @@
     err=${?}
   fi
 
-  echo "${D}"
+  echo "${D}" >&2
   [ ${err} = 0 ] &&
     [ X"${D}" = X"${D##*setup failed}" ] &&
     [ X"${D}" != X"${D##*[Uu]sing overlayfs}" ] &&
@@ -1575,10 +1575,10 @@
     die -t ${T} "setup for overlayfs"
   D=`adb remount 2>&1`
   err=${?}
-  echo "${D}"
+  echo "${D}" >&2
   [ ${err} != 0 ] ||
     [ X"${D}" = X"${D##*remount failed}" ] ||
-    ( echo "${D}" && false ) ||
+    ( echo "${D}" && false ) >&2 ||
     die -t ${T} "remount failed"
 fi
 
@@ -1644,7 +1644,7 @@
   die "/vendor is not read-only"
 adb_su remount vendor </dev/null ||
   die "remount command"
-adb_su df -k </dev/null | skip_unrelated_mounts
+adb_su df -k </dev/null | skip_unrelated_mounts >&2
 adb_sh grep " /vendor .* rw," /proc/mounts >/dev/null </dev/null ||
   die "/vendor is not read-write"
 adb_sh grep " \(/system\|/\) .* rw," /proc/mounts >/dev/null </dev/null &&