There are a few commands which will help us determine any information about running system.

lscpu CPU architecture

lshw hardware information

hwinfo hardware information (grouped)

hwinfo --network network interfaces

hwinfo --disk partitions/USB sticks

lsscsi devices info

lsblk block devices with partitions

inxi great tool with many options to retireve any system info

df pydf fdisk disk info, usage & mounts

free -m RAM status

/proc

nproc number of CPU cores

uname -a kernel info

lsmod list loaded modules

modinfo <module name> display info about <module name>

dmidecode see details about the RAM

/etc/services stores information about numerous services that client applications might use on the host

/proc/loadavg display load average numbers

/proc/cpuinfo info about processors