How to find number of cores in Ubuntu (or other versions of Linux)?

  If you’re using a virtual server (whether online or your own physical machine) it can be handy sometimes to check how many CPU cores are available; here are two easy methods of doing this. The first:  
nproc
  This will return a single number, whether it be 1, 2, 4 or otherwise. For a more detailed look, try:  
lscpu
  This will usually give a more complex readout, e.g.:  
[email protected] [/]# lscpu Architecture:          x86_64 CPU op-mode(s):        32-bit, 64-bit Byte Order:            Little Endian CPU(s):                1 On-line CPU(s) list:   0 Thread(s) per core:    1 Core(s) per socket:    1 CPU socket(s):         1 NUMA node(s):          1 Vendor ID:             GenuineIntel CPU family:            6 Model:                 45 Stepping:              7 CPU MHz:               2000.024 BogoMIPS:              4000.04 Hypervisor vendor:     Xen Virtualization type:   para L1d cache:             32K L1i cache:             32K L2 cache:              256K L3 cache:              15360K NUMA node0 CPU(s):     0