How to get detailed information about the machine's CPU in Linux

You can run the following command to see all information about the processors of the machine
    less /proc/cpuinfo

Note: This file shows logical cpu's seen by the OS on the machine, i.e. the CPU shown can be
- physical CPU
- hyperthreading 
- shared (e.g. dual or quad) core


Following command will return number of physical CPU's
    cat /proc/cpuinfo | egrep '(physical id).*:'  | sort -u | wc -l

Following command will return number of shared cores
    cat /proc/cpuinfo | egrep '(cpu cores).*:' | awk -F ":" '{print $2}'   | sort | uniq

If following command returns 1 then hyper-threading is disabled on then machine, if  >1 then hyper threading is enabled on the machine
    echo $(( `cat /proc/cpuinfo | egrep '(siblings).*:' | awk -F ":" '{print $2}'   | sort | uniq` \
           / `cat /proc/cpuinfo | egrep '(cpu cores).*:' | awk -F ":" '{print $2}'   | sort | uniq` ))

To get total virtual processors available to the OS, multiply above 3 values.