Determine the operating system from the command line

which_os.sh

###########################################################
# Determine the operating system from the command line
#
# NB: Only handles Ubuntu, CentOS, and MacOS so far
###########################################################
function which_os() {
    # Setup an OSNAME variable to capture the OS's name
    OSNAME='Unknown';

    # If there is an /etc/os-release file, use that
    if [[ -f "/etc/os-release" ]]
    then
        OSINFO=`cat /etc/os-release`;
    else
    # Otherwise use the uname -a command
        OSINFO=`uname -a`
    fi

    # Try and find the OS name in the OS info
    case $OSINFO in
        *'Ubuntu'*)
            OSNAME='Ubuntu'
            ;;
        *'CentOS'*)
            OSNAME='CentOS'
            ;;
        *'Darwin'*)
            OSNAME='MacOS'
            ;;
    esac

    echo $OSNAME;
}