$ cat /proc/meminfo
sudo dmidecode --type 17
free -m
free -h --si
# produces human readable output, in SI units of MB, GB, etc.
free -g
sudo dmidecode --type 17 | more
for more information search this webside --
https://www.howtogeek.com/659529/how-to-check-memory-usage-from-the-linux-terminal/