a) dmesg command – Display the OpenBSD system message buffer including boot time info.

b) sysctl command – Display or set the OpenBSD system sysctl (kernel) variables.

Method #1: Display real and user installed memory on OpeBSD

Type the following command:
# dmesg | grep -i mem
OR
# grep -i mem /var/run/dmesg.boot
Sample outputs:

real mem = 3500277760 (3338MB)
avail mem = 3398483968 (3241MB)

Method #2: OpenBSD show installed RAM memory size

Type the following command

sysctl hw | grep mem

OR

sysctl  | grep -i hw.\*mem

Sample outputs:

hw.physmem=3500277760
hw.usermem=3500253184

Or simply get full hardware info, type:

sysctl hw

Sample outputs: