Shell-进阶

shell高级

#!/bin/bash
set -o nounset
set -o errexit

判断系统

# 判断内核版本，2开头的内核是低版本
if [[ $(uname -r | cut -d "." -f 1) -eq 2 ]]; then
    echo "The system is running an old kernel, which is incompatible with this installer."
    exit
fi
# 检测系统版本，获取安装命令
if [[ -f /etc/redhat-release ]]; then
    release="centos"
    systemPackage="yum"
    systempwd="/usr/lib/systemd/system/"
elif cat /etc/issue | grep -Eqi "debian"; then
    release="debian"
    systemPackage="apt-get"
    systempwd="/lib/systemd/system/"
elif cat /etc/issue | grep -Eqi "ubuntu"; then
    release="ubuntu"
    systemPackage="apt-get"
    systempwd="/lib/systemd/system/"
elif cat /etc/issue | grep -Eqi "centos|red hat|redhat"; then
    release="centos"
    systemPackage="yum"
    systempwd="/usr/lib/systemd/system/"
elif cat /proc/version | grep -Eqi "debian"; then
    release="debian"
    systemPackage="apt-get"
    systempwd="/lib/systemd/system/"
elif cat /proc/version | grep -Eqi "ubuntu"; then
    release="ubuntu"
    systemPackage="apt-get"
    systempwd="/lib/systemd/system/"
elif cat /proc/version | grep -Eqi "centos|red hat|redhat"; then
    release="centos"
    systemPackage="yum"
    systempwd="/usr/lib/systemd/system/"
fi
# 判断系统类型
if grep -qs "ubuntu" /etc/os-release; then
    os="ubuntu"
    os_version=$(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=$(grep -oE '[0-9]+' /etc/fedora-release | head -1)
    group_name="nobody"
else
    echo "This installer seems to be running on an unsupported distribution.
Supported distributions are Ubuntu, Debian, CentOS, and Fedora."
    exit
fi
# 判断系统版本版本
if [[ "$os" == "ubuntu" && "$os_version" -lt 1804 ]]; then
    echo "Ubuntu 18.04 or higher is required to use this installer.
This version of Ubuntu is too old and unsupported."
    exit
fi
if [[ "$os" == "debian" && "$os_version" -lt 9 ]]; then
    echo "Debian 9 or higher is required to use this installer.
This version of Debian is too old and unsupported."
    exit
fi
if [[ "$os" == "centos" && "$os_version" -lt 7 ]]; then
    echo "CentOS 7 or higher is required to use this installer.
This version of CentOS is too old and unsupported."
    exit
fi

文件写入

#高级的 写入文件语法
new_client () {
    # Generates the custom client.ovpn
    {
    cat /etc/openvpn/server/client-common.txt
    echo "<ca>"
    cat /etc/openvpn/server/easy-rsa/pki/ca.crt
    echo "</ca>"
    echo "<cert>"
    sed -ne '/BEGIN CERTIFICATE/,$ p' /etc/openvpn/server/easy-rsa/pki/issued/"$client".crt
    echo "</cert>"
    echo "<key>"
    cat /etc/openvpn/server/easy-rsa/pki/private/"$client".key
    echo "</key>"
    echo "<tls-crypt>"
    sed -ne '/BEGIN OpenVPN Static key/,$ p' /etc/openvpn/server/tc.key
    echo "</tls-crypt>"
    } > ~/"$client".ovpn
}
# 普通的写入
cat > /root/1.txt <<EOF
echo test
EOF

root启动

function Msg(){
  if [ $? -eq 0 ];then
    action "$1" /bin/true
  else
    action "$1" /bin/false
  fi
}
if ! [ $UID -eq 0 ]
then
  Msg "请使用超级用户执行本脚本"  ; exit 0
fi

ctrl+c终止程序

#!/bin/bash
# 按任意键执行程序，ctrl+c则终止程序
get_char(){
    SAVEDSTTY=`stty -g`
    stty -echo
    stty cbreak
    dd if=/dev/tty bs=1 count=1 2> /dev/null
    stty -raw
    stty echo
    stty $SAVEDSTTY
}
echo "Press any key to start...or Press Ctrl+c to cancel"
char=`get_char`
echo "我执行成功了"

字体颜色

yellow(){
    echo -e "\033[33m\033[01m$1\033[0m"
}
green(){
    echo -e "\033[32m\033[01m$1\033[0m"
}
red(){
    echo -e "\033[31m\033[01m$1\033[0m"
}
red "======================================================================="
red "检测到SELinux为宽容状态，为防止申请证书失败，请先重启VPS后，再执行本脚本"
red "======================================================================="
green "======================="
yellow "请输入绑定到本VPS的域名"
green "======================="

脚本生成脚本文件

# 解决相对路径问题
cd `dirname $0`
# 引入外部文件
source ../common/util.sh
# 备份
cp ${SSH_FILE_PATH}{,.bak}

选择功能

随机数

整数随机数

echo $[$RANDOM%19+9]
echo $[$RANDOM%4+3]
echo $[$RANDOM%20+500] #生成500-520的整数

输出帮助

:/usr/bin:/root/bin
usage () {
  echo "Usage: $0 [OPTION]"
  echo "-d, --dest=name       Destination directory. Default is /tmp"
  echo "-h, --help            Display this help and exit."
  echo "-p, --password[=name] Password to use when connecting to server. If password is"
  echo "                      not given it's asked from the tty."
  echo "-t                    Temporary mount point for the snapshot. Default is /mnt."
  echo "-u, --user=name       User for login if not current user"
  exit 1
}
case "$1" in
    * )
    usage
    ;;
esac

cat /etc/passwd |cut -f 1 -d : #只显示用户名，cut分割
cat /etc/group |cut -f 1 -d : #只显示组名

瓦雀