if [ X"${KERNEL_NAME}" == X'LINUX' ]; then # Directory of RC scripts. export DIR_RC_SCRIPTS='/etc/init.d' if [ -f /etc/redhat-release ]; then # RHEL/CentOS export DISTRO='RHEL' # Get distribution version if grep '\ 6' /etc/redhat-release &>/dev/null; then # version 6.x export DISTRO_VERSION='6' elif grep '\ 7' /etc/redhat-release &>/dev/null; then # version 7.x export DISTRO_VERSION='7' else export UNSUPPORTED_RELEASE='YES' fi # Get distribution name as DISTRO_CODENAME if grep '^Red' /etc/redhat-release &>/dev/null; then # RHEL export DISTRO_CODENAME='rhel' elif grep '^CentOS' /etc/redhat-release &>/dev/null; then # CentOS export DISTRO_CODENAME='centos' elif grep '^Scientific' /etc/redhat-release &>/dev/null; then # Scientific Linux export DISTRO_CODENAME='scientific' else export UNSUPPORTED_RELEASE='YES' fi elif [ -f /etc/lsb-release ]; then # Ubuntu export DISTRO='UBUNTU' # Ubuntu version number and code name: # - 14.04: trusty # - 15.04: vivid export DISTRO_ID="$(grep 'DISTRIB_ID' /etc/lsb-release | awk -F'=' '{print $2}')" export DISTRO_VERSION="$(grep 'DISTRIB_RELEASE' /etc/lsb-release | awk -F'=' '{print $2}')" export DISTRO_CODENAME="$(grep 'DISTRIB_CODENAME' /etc/lsb-release | awk -F'=' '{print $2}')" # Unsupported releases: 12.x, 13.x, 14.10 if echo "${DISTRO_VERSION}" | grep -E '^(12|13|14\.10)' &>/dev/null ; then export UNSUPPORTED_RELEASE='YES' fi elif [ -f /etc/debian_version ]; then # Debian export DISTRO='DEBIAN' # Get major release version number export DISTRO_VERSION="$(cat /etc/debian_version)" # Set distro code name and unsupported releases. if grep '^7' /etc/debian_version &>/dev/null || \ grep -i '^wheezy' /etc/debian_version &>/dev/null; then export DISTRO_VERSION='7' export DISTRO_CODENAME='wheezy' elif grep '^8' /etc/debian_version &>/dev/null || \ grep -i '^jessie' /etc/debian_version &>/dev/null; then export DISTRO_VERSION='8' export DISTRO_CODENAME='jessie' else export UNSUPPORTED_RELEASE='YES' fi # Override settings. export SHELL_NOLOGIN='/usr/sbin/nologin' else export UNSUPPORTED_RELEASE='YES' fi elif [ X"${KERNEL_NAME}" == X'FREEBSD' ]; then export DISTRO='FREEBSD' export DISTRO_VERSION="$(uname -r |awk -F'[.-]' '{print $1}')" # Directory of RC scripts. export DIR_RC_SCRIPTS='/usr/local/etc/rc.d' export PYTHON_BIN='/usr/local/bin/python' # Unsupported releases: 7, 8. if echo "${DISTRO_VERSION}" | grep '^[78]' &>/dev/null ; then export UNSUPPORTED_RELEASE='YES' fi export SHELL_BASH='/usr/local/bin/bash' # Default password scheme. export DEFAULT_PASSWORD_SCHEME='BCRYPT' elif [ X"${KERNEL_NAME}" == X'OPENBSD' ]; then export DISTRO='OPENBSD' export DISTRO_VERSION="$(uname -r)" # Directory of RC scripts. export DIR_RC_SCRIPTS='/etc/rc.d' export RC_CONF_LOCAL='/etc/rc.conf.local' export SHELL_BASH='/usr/local/bin/bash' export PYTHON_BIN='/usr/local/bin/python' # Unsupported release: 5.6 and earlier versions. if echo "${DISTRO_VERSION}" | grep '^5.[123456]' &>/dev/null ; then export UNSUPPORTED_RELEASE='YES' fi # Default password scheme. export DEFAULT_PASSWORD_SCHEME='BCRYPT' else # Not support *BSD and other distrobutions yet. echo "Error: Your OS is not supported yet." exit 255 fi代碼比較長,不過脈絡比較清晰,首先根據KERNEL_NAME的值判斷是哪種操作系統,作者給出的判斷是3種,分別是LINUX OPENBSD FREEBSD , 也就是該腳本只能在這3種平台上進行部署,如果需要自己擴展的話,就可以在增加新的判斷,最後如果3種都不是的話,就直接返回255,如下代碼: echo "Error: Your OS is not supported yet." exit 255 接下來分析當KERNEL_NAME的值為LINUX,腳本做了什麼,首先定義了一個變量 export DIR_RC_SCRIPTS='/etc/init.d' linux中一般啟動腳本都是放在這個目錄裡的,LINUX本身也有很多版本,因此作者在此處又進行多種類型的判斷,判斷的依據文件分別是/etc/redhat-release /etc/lsb-release /etc/debian_version這3種文件分別對應rhel/centos ubuntu debian , 從而也說明在LINUX的版本中,只支持這3種,其他的LINUX版本是不支持的,最後作者返回一句代碼: 定義了一個UNSUPPORTED_RELEASE變量,在後續的代碼應該會調用這個變量來判斷是否支持。 針對這3種LINUX,作者又具體細分到不同的小版本中,首先看rhel/centos 系列,下面代碼: 首先根據存在redhat-release文件,定義了DISTRO的值 if [ -f /etc/redhat-release ]; then export DISTRO='RHEL' 這樣在get_all.sh的腳本裡調用時就有了判斷依據,接著判斷具體的版本,
if grep '\ 6' /etc/redhat-release &>/dev/null; then # version 6.x export DISTRO_VERSION='6' elif grep '\ 7' /etc/redhat-release &>/dev/null; then # version 7.x export DISTRO_VERSION='7' else export UNSUPPORTED_RELEASE='YES' fi顯然只支持6和7兩個版本,也就是安裝時,如果不是這2個版本的話,就會返回unsupport_release的值為YES了。 rhel還有兩個個反編譯版本即centos ,Scientific Linux, 因此作者又定義了一個變量來區別 DISTRO_CODENAME, 代碼如下:
if grep '^Red' /etc/redhat-release &>/dev/null; then # RHEL export DISTRO_CODENAME='rhel' elif grep '^CentOS' /etc/redhat-release &>/dev/null; then # CentOS export DISTRO_CODENAME='centos' elif grep '^Scientific' /etc/redhat-release &>/dev/null; then # Scientific Linux export DISTRO_CODENAME='scientific' else export UNSUPPORTED_RELEASE='YES' fi顯然在/etc/redhat-release文件裡,不同的發行版本有不同的關鍵字,這樣關於紅帽系的操作系統,作者就已經區分完畢了。 接下來關於ubuntu的判斷就簡單多了,看圖 根據/etc/lsb-release的文件是否存在,賦值DISTRO為UBUNTU,然後判斷具體版本,看代碼
export DISTRO_ID="$(grep 'DISTRIB_ID' /etc/lsb-release | awk -F'=' '{print $2}')" export DISTRO_VERSION="$(grep 'DISTRIB_RELEASE' /etc/lsb-release | awk -F'=' '{print $2}')" export DISTRO_CODENAME="$(grep 'DISTRIB_CODENAME' /etc/lsb-release | awk -F'=' '{print $2}')" # Unsupported releases: 12.x, 13.x, 14.10 if echo "${DISTRO_VERSION}" | grep -E '^(12|13|14\.10)' &>/dev/null ; then export UNSUPPORTED_RELEASE='YES' fi從程序可以看出UBUNTU的ID , RELEASE , CODENAME的值都在/etc/lsb-release的文件裡,用grep 和awk匹配後,賦予不同變量的值。 用grep 篩選出系統版本為12,13,14.10的都為不支持版本,目前支持的版本為14.04,15.04 接下來判斷的就是DEBIAN了,同樣是判斷文件,如圖: 文件存在,則DISTRO的值為DEBIAN,接下來判斷版本號: # Get major release version number export DISTRO_VERSION="$(cat /etc/debian_version)" cat /etc/debian_version 一個命令就可以得到具體版本,比rhel更容易判斷 接下來對具體版本進行判斷,見代碼:
# Set distro code name and unsupported releases. if grep '^7' /etc/debian_version &>/dev/null || \ grep -i '^wheezy' /etc/debian_version &>/dev/null; then export DISTRO_VERSION='7' export DISTRO_CODENAME='wheezy' elif grep '^8' /etc/debian_version &>/dev/null || \ grep -i '^jessie' /etc/debian_version &>/dev/null; then export DISTRO_VERSION='8' export DISTRO_CODENAME='jessie' else export UNSUPPORTED_RELEASE='YES' fi
顯然只支持DEBIAN的7,8兩個版本,到此DISTRO的值和操作系統的判斷結束,如果想新增特殊操作系統的話或者自己定義的話,在此處加入自己的代碼即可。