Below you can find few ways on how to determine CoreOS version number.
First method is dome simply by login. Every time you login to your CoreOS system a “Message of the day” located in
/etc/motd is displayed:
Last login: Thu Dec 10 09:05:41 2015 from 10.0.0.8 CoreOS stable (835.9.0)
Alternatively, see the content
# cat /etc/motd CoreOS stable (835.9.0)
Another and preferred method is to consult the content of
# cat /etc/os-release NAME=CoreOS ID=coreos VERSION=835.9.0 VERSION_ID=835.9.0 BUILD_ID= PRETTY_NAME="CoreOS 835.9.0" ANSI_COLOR="1;32" HOME_URL="https://coreos.com/" BUG_REPORT_URL="https://github.com/coreos/bugs/issues"
Both methods above only gave us CoreOS version number and version ID. To retrieve a CoreOS code along with a version number see a content of the
# cat /etc/lsb-release DISTRIB_ID=CoreOS DISTRIB_RELEASE=835.9.0 DISTRIB_CODENAME="Red Dog" DISTRIB_DESCRIPTION="CoreOS 835.9.0"