remove-old-kernels: Change confirmation logic

Handle confirmation dialog in remove-old-kernels deterministically and always
pass `-y' to apt-get. By this we can be sure that confirmation is always asked.
(Because apt-get could skip its confirmation dialog.) Also, `--force' is not
(and never was) contradictory with `--dry-run'.

Signed-off-by: Vitaly Chikunov <vt@altlinux.org>

remove-old-kernels

@@ -39,7 +39,7 @@ show_help()
         cat <<EOF
 Usage: $PROG [options]
 Valid options are:
-	-f, -y, --force   non-interactive kernel removal (default is interactive)
+	-f, -y, --force   do not ask for removal confirmation (default is to ask)
 	-n, --dry-run     just simulate removal
 	-t, --type        remove kernels with specified flavour (ovz-smp, std-def, etc)
 	-a, --all         remove kernels with all flavours
@@ -71,10 +71,6 @@ while :; do
 	shift
 done
 
-if [ -n "$force" ] && [ -n "$dryrun" ]; then
-	show_usage '--force and --dry-run are mutually exclusive options.'
-fi
-
 if [ -n "$kernel_flavour" ] && [ -n "$all" ]; then
 	show_usage '--type and --all are mutually exclusive options.'
 fi
@@ -166,9 +162,13 @@ for kernel_flavour in $flavours; do
 		fi
 	done
 done
-echo "Not removing these kernels (reason why keeping):"
+howmuch=$(echo "$keep_kernels" | grep -c .)
+[ "$howmuch" -eq 1 ] && phrase="this kernel" || phrase="these $BRIGHT$howmuch$NORM kernels"
+echo "Not removing $phrase (reason why keeping):"
 echo "$keep_kernels"
-echo "Removing these kernels:"
+howmuch=$(echo "$remove_kernels" | grep -c .)
+[ "$howmuch" -eq 1 ] && phrase="this kernel" || phrase="these $BRIGHT$howmuch$NORM kernels"
+echo "Removing $phrase:"
 echo "$remove_kernels"
 
 if [ -z "$apt_args_list" ] ; then
@@ -180,8 +180,26 @@ if [ "$UID" != "0" ]; then
 	echo >&2 "${RED}Warning: This program requires root privileges.$NORM"
 fi
 
+echo -n "Confirm" ${dryrun:+--dry-run} "uninstall action for $phrase [Y/n]? "
+if [ -n "$force" ]; then
+	echo "yes"
+else
+	while true; do
+		read -r || { echo "Aborting"; exit 1; }
+		shopt -s nocasematch
+		case "$REPLY" in
+			n|no|q) exit 0 ;;
+			y|ye|yes|'') break ;;
+			*) ;;
+		esac
+		echo -n "[Y/n] "
+		shopt -u nocasematch
+	done
+fi
+
+
 # shellcheck disable=SC2086
-V apt-get $force $dryrun remove $apt_args_list
+V apt-get -y $dryrun remove $apt_args_list
 
 # Mask non-zero apt exit code on dry run:
 if [ -n "$dryrun" ]; then