Excluding loop devices from being considered

xorriso-dd-target/xorriso-dd-target

@@ -261,6 +261,17 @@ arg_interpreter() {
   fi
 }
 
+## Obtain a blank separated list of top-level names which do not look like
+## CD, floppy, RAM dev, or loop device.
+collect_devices() {
+  "$lsblk_cmd" -d -n -o NAME \
+    | grep -v '^sr[0-9]' \
+    | grep -v '^fd[0-9]' \
+    | grep -v '^zram[0-9]' \
+    | grep -v '^loop[0-9]' \
+    | tr '\n\r' '  '
+}
+
 ## Trying to find the desired device by watching plug-in effects
 plug_in_watcher() {
   found_devices=
@@ -274,7 +285,7 @@ plug_in_watcher() {
   echo "and then unplug it." >&2
   echo "Press the Enter key when ready." >&2
   read dummy
-  old_device_list=' '$("$lsblk_cmd" -d -n -o NAME  | grep -v '^sr[0-9]' | grep -v '^fd[0-9]' | tr '\n\r' '  ')' '
+  old_device_list=' '$(collect_devices)' '
 
 # <<< Mock-up to save USB socket wear-off by erasing items from old_device_list
 # <<< Their presence in new_device_list will let them appear as fresh plugs
@@ -289,7 +300,7 @@ plug_in_watcher() {
   end_time="$(expr $(date +'%s') + 10)"
   while test $(date +'%s') -le "$end_time"
   do
-    new_device_list=' '$("$lsblk_cmd" -d -n -o NAME  | grep -v '^sr[0-9]' | grep -v '^fd[0-9]' | tr '\n\r' '  ')' '
+    new_device_list=' '$(collect_devices)' '
     if test "$old_device_list" = "$new_device_list"
     then
       sleep 1
@@ -345,8 +356,7 @@ list_devices() {
   if test -z "$devs"
   then
     # Obtain list of top-level names which do not look like CD, floppy, RAM dev
-    devs=$("$lsblk_cmd" -d -n -o NAME | grep -v '^sr[0-9]' \
-           | grep -v '^fd[0-9]' | grep -v '^zram[0-9]')
+    devs=$(collect_devices)
   fi
   
   not_advised=0
@@ -692,7 +702,12 @@ then
       write_image "$image_file" $candidates
       exit $?
     else
-      echo "Would write to /dev/$candidates if an -image_file were given."
+      if test -n "$dummy_run"
+      then
+        echo "Would simulate writing to /dev/$candidates if an -image_file were given."
+      else
+        echo "Would write to /dev/$candidates if an -image_file were given."
+      fi
       exit 0
     fi
   elif test "$num_cand" -gt 1