Create sensor to show only today's day "number" (i.e. 2017-09-05, my sensor would output the "05")

Just curious if it’s possible to extract or read from my date sensor that I already have that shows the year, month, day to output a new sensor that just shows the day only. Some way to read what shows after the second dash only in the following example

sensor.date current state: 2017-09-10

then my new sensor would be showing just the number 10

Here are two.
the sensor today would show the 9th as 9 the sensor ztoday would show the 9th as 09 just depends on which way you want it:

sensor:
  - platform: template
    sensors:
      today:
        value_template: '{{now().strftime("%d")}}'
      ztoday:
        value_template: '{{now().strftime("%-d")}}'

This is perfect, thanks!

Just barely updated to Hass.io and now this isn’t working for me, it just outputs blank now. Here’s how I have it setup:

sensor:
  - platform: template
    sensors:
      today_number:
        value_template: '{{now().strftime("%-d")}}'

Dub,
I assume you got this fixed but no-one revisted the topic to say how.
I believe that HA stopped updating now() so basically it get read and interpreted at boot and thence no more.
What you should do is place an “entity_id: sensor.date” above the value_template (but indented as per the sensor name (today_number), the system will then update the value when ‘date’ changes