View Hardware details of Linux machine:

CPU:
more /proc/cpuinfo

To count processor (including cores), enter:
grep -c processor /proc/cpuinfo


HDD:

df -h
fdisk -l
parted -l

RAM:

more /proc/meminfo
cat /proc/meminfo
free -k
free -m
free -g
dmidecode -t 16 --maximum limit
dmidecode -t 17




linux kernel version info:
--------------------------
# uname -a

whether 64-bit or not:
# uname -mrs

pae - pae kernel type indicate that I'm accssing more than 4GB ram using 32 bit kernel.
SMP - Kernel that supports multi core and multiple cpus.

Distribution Version:
# cat /etc/*release
# cat /etc/*-release
# lsb_release -a
# cat /proc/version