How do I find out my FreeBSD server version and patch level of the installed system using command line option?

You can use any one of the following command to display the FreeBSD operating system version and patch level:

a) freebsd-version command – Show the version and patch level of the installed system

b) uname command – Show information about the system

Say hello to freebsd-version command

The freebsd-version command appeared in FreeBSD version 10.0. To see the version and patch level of the installed kernel:
freebsd-version -k
To see the version and patch level of the installed userland:
freebsd-version -u
Sample outputs:

You can see a system being repaired using a live CD:
mount -rt ufs /dev/ada0p2 /mnt
env ROOT=/mnt /mnt/bin/freebsd-version -ku

You can also use the following command to find out if FreeBSD kernel is running in 32bit or 64bit mode:
# getconf LONG_BIT
Sample outputs:

64

Old good uname command

Type the following command (it works on all versions of FreeBSD):
umame -a
uname -mrs
Outputs:

FreeBSD 10.1-RELEASE-p10 amd64