This shell script find out which distro and version of *nix os used.

detect-nix-os.sh

#!/bin/sh
# Detects which OS and if it is Linux then it will detect which Linux Distribution.
# Thanks to this contribution that we take it from this site: 
# http://www.unix.com/unix-for-advanced-and-expert-users/21468-machine.html#post83185
# Test result on ubuntu 14.04 LTS:
# Linux Debian jessie/sid ( 3.13.0-32-generic x86_64)

OS=`uname -s`
REV=`uname -r`
MACH=`uname -m`

GetVersionFromFile()
{
        VERSION=`cat $1 | tr "\n" ' ' | sed s/.*VERSION.*=\ // `
}

if [ "${OS}" = "SunOS" ] ; then
        OS=Solaris
        ARCH=`uname -p`
        OSSTR="${OS} ${REV}(${ARCH} `uname -v`)"
elif [ "${OS}" = "AIX" ] ; then
        OSSTR="${OS} `oslevel` (`oslevel -r`)"
elif [ "${OS}" = "Linux" ] ; then
        KERNEL=`uname -r`
        if [ -f /etc/redhat-release ] ; then
                DIST='RedHat'
                PSUEDONAME=`cat /etc/redhat-release | sed s/.*\(// | sed s/\)//`
                REV=`cat /etc/redhat-release | sed s/.*release\ // | sed s/\ .*//`
        elif [ -f /etc/SuSE-release ] ; then
                DIST=`cat /etc/SuSE-release | tr "\n" ' '| sed s/VERSION.*//`
                REV=`cat /etc/SuSE-release | tr "\n" ' ' | sed s/.*=\ //`
        elif [ -f /etc/mandrake-release ] ; then
                DIST='Mandrake'
                PSUEDONAME=`cat /etc/mandrake-release | sed s/.*\(// | sed s/\)//`
                REV=`cat /etc/mandrake-release | sed s/.*release\ // | sed s/\ .*//`
        elif [ -f /etc/debian_version ] ; then
                DIST="Debian `cat /etc/debian_version`"
                REV=""

        fi
        if [ -f /etc/UnitedLinux-release ] ; then
                DIST="${DIST}[`cat /etc/UnitedLinux-release | tr "\n" ' ' | sed s/VERSION.*//`]"
        fi

        OSSTR="${OS} ${DIST} ${REV}(${PSUEDONAME} ${KERNEL} ${MACH})"

fi

echo ${OSSTR}