improve post-setup serial console setup

diff --git a/preseed/jessie/commands/late_commands.d/enable_serial_console b/preseed/jessie/commands/late_commands.d/enable_serial_console
index 09f8acb8c689e8bee8b9ae1042a4d1388e422623..47768c0b2cdee7827957fd636abbdf482ea76971 100755 (executable)
--- a/preseed/jessie/commands/late_commands.d/enable_serial_console
+++ b/preseed/jessie/commands/late_commands.d/enable_serial_console
@@ -1,9 +1,15 @@
 #!/bin/sh
 echo "Enabling the serial console..."
-#683124 requires the cmdline patch, and #444026 is for GRUB_TERMINAL:
-sed -i -e '/^GRUB_CMDLINE_LINUX=/s/"$/ console=tty0 console=ttyS0,115200n8&/' \
-       -e '/^GRUB_CMDLINE_LINUX=/s/=" /="/' \
-       -e '/^GRUB_TERMINAL=/s/serial/"& console"/' \
-       /etc/default/grub
-update-grub
-sed -i '/ttyS0/s/^#//;/ttyS0/s/9600 vt100/115200 linux/' /etc/inittab
+if [ -f /etc/default/grub ]; then
+  #683124/#769406 requires the cmdline patch, and #444026 is for GRUB_TERMINAL:
+  sed -i -e '/^GRUB_CMDLINE_LINUX=/s/"$/ console=tty0 console=ttyS0,115200n8&/' \
+        -e '/^GRUB_CMDLINE_LINUX=/s/=" /="/' \
+        -e '/^GRUB_TERMINAL=/s/serial/"& console"/' \
+        /etc/default/grub
+  update-grub
+fi
+if [ -f /etc/inittab ]; then
+  sed -i '/ttyS0/s/^#//;/ttyS0/s/9600 vt100/115200 linux/' /etc/inittab
+else
+  echo "Not setting up a TTY on the serial port, presumably systemd will..."
+fi