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shell脚本判断系统类型

1.场景说明

在生产环境中服务器的系统类型可能会有多种，例如有CentOS、Ubuntu、Debian等等，在做批量操作(如shell脚本、ansible等)的时候就需要对服务器等系统类型做判断，然后执行不同的命令，例如执行安装命令，CentOS系统执行 yum 命令，Ubuntu、Debian执行 apt 命令

2.判断方法

这里以常用的Ubuntu和CentOS为例

2.1 CentOS

方法一 查看文件

/etc/redhat-release

$ cat /etc/redhat-release 
CentOS Linux release 7.8.2003 (Core)

/etc/centos-release

$ cat /etc/centos-release
CentOS Linux release 7.8.2003 (Core)

/etc/issue

# CentOS6中会显示具体版本，CentOS7中显示如下
$ cat /etc/issue
\S
Kernel \r on an \m

/etc/os-release

$ cat /etc/os-release 
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"

CENTOS_MANTISBT_PROJECT="CentOS-7"
CENTOS_MANTISBT_PROJECT_VERSION="7"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="7"

方法二 通过命令

命令 lsb_release，通过 yum -y install redhat-lsb-core 安装

$ lsb_release -a
LSB Version:	:core-4.1-amd64:core-4.1-noarch
Distributor ID:	CentOS
Description:	CentOS Linux release 7.8.2003 (Core)
Release:	7.8.2003
Codename:	Core

2.2 Ubuntu

方法一 查看文件

$ cat /etc/issue
Ubuntu 16.04.1 LTS \n \l

方法二 通过命令

命令 lsb_release ，通过 apt -y install lsb-core 安装

$ lsb_release 
LSB Version:	core-9.20160110ubuntu0.2-amd64:core-9.20160110ubuntu0.2-noarch:security-9.20160110ubuntu0.2-amd64:security-9.20160110ubuntu0.2-noarch

3.最佳判断方法

在生产我们常用的方法就是根据 /etc/os-release 返回的内容进行判断

openvpn一键安装脚本 中有写对系统类型的判断

# Detect OS
# $os_version variables aren't always in use, but are kept here for convenience
if grep -qs "ubuntu" /etc/os-release; then
	os="ubuntu"
	os_version=$(grep 'VERSION_ID' /etc/os-release | cut -d '"' -f 2 | tr -d '.')
	group_name="nogroup"
elif [[ -e /etc/debian_version ]]; then
	os="debian"
	os_version=$(grep -oE '[0-9]+' /etc/debian_version | head -1)
	group_name="nogroup"
elif [[ -e /etc/centos-release ]]; then
	os="centos"
	os_version=$(grep -oE '[0-9]+' /etc/centos-release | head -1)
	group_name="nobody"
elif [[ -e /etc/fedora-release ]]; then
	os="fedora"
	os_version=$(grep -oE '[0-9]+' /etc/fedora-release | head -1)
	group_name="nobody"
else
	echo "This installer seems to be running on an unsupported distribution.
Supported distributions are Ubuntu, Debian, CentOS, and Fedora."
	exit
fi

判断示例

$ grep -w NAME /etc/os-release |awk -F'[="]+' '{print $2}'
CentOS Linux

$ grep -w NAME /etc/os-release |awk -F'[="]+' '{print $2}'
Ubuntu