自动化运维（一）：Shell编程基础

yum install make gcc patch zlib-devel bzip2 bzip2-devel readline-devel sqlite sqlite-devel openssl-devel tk-devel libffi-devel xz-devel libuuid-devel gdbm-devel

# 安装
curl https://pyenv.run | bash
# 设置环境变量
echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrc
echo 'command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(pyenv init -)"' >> ~/.bashrc
# 重启shell
exec "$SHELL"

# 列出可用版本
pyenv install -l
# 安装3.8.16版本
pyenv install 3.8.16
# 创建一个3.8.16版本的虚拟环境, 命名为imooc-ops
pyenv virtualenv 3.8.16 imooc-ops
# 列出虚拟环境
pyenv virtualenvs
# 激活imooc-ops环境
pyenv activate imooc-ops
# 关闭环境
pyenv deactivate

echo "hello,      world"
echo  hello,        world,        你好  # 长段空格会压缩成1个空格
# 结果是 hello, world, 你好
var1="a  b          c      d"
echo $var1      # 只保留1个空格
echo "$var1"    # 保持长段空格

# -n
echo "hello"      # 默认输出的最后会有一个换行符
echo -n "hello"   # 不要加默认的换行符

echo        # 输出一个换行符
echo -n "please input your name: "
read name   # 输入读到name变量
echo "hello, $name"

# -e
echo "hello\nwor\tld"        # 转义并没有被解释
echo -e "hello\nwor\tld"     # 允许转义

echo -e "\033[31mhello\033[0m"    # 输出红色hello
# 各种文本颜色
echo -e "\033[30m 黑色字 \033[0m"
echo -e "\033[31m 红色字 \033[0m"
echo -e "\033[32m 绿色字 \033[0m"
echo -e "\033[33m 黄色字 \033[0m"
echo -e "\033[34m 蓝色字 \033[0m"
echo -e "\033[35m 紫色字 \033[0m"
echo -e "\033[36m 青色字 \033[0m"
echo -e "\033[37m 白色字 \033[0m"
# 40m 到 47m 代表不同的背景颜色，使用方式同上

var1=hello
echo $var1
var1_xyz=abc
# 期望：输出$var1_xyz=hello_xyz
echo "输出\$var1_xyz=$var1_xyz"
# 实际：输出$var1_xyz=abc

echo "继续输出: ${var1}_xyz"    # 成功

var2=123    # 直接给变量赋值
# declare 显示声明变量
# -i 指定整型  -r 只读变量 -a 指定数组  -f 指定函数名   
declare -i var3
var3=xyz            # 赋值语句失败
echo "\$var3=$var3" # var3解释为0

var3=245    # 赋值成功
echo "\$var3=$var3"

declare -r var4=abc   # 只读变量，需声明时赋值
# var4=xyz    失败，shell报错
echo $var4

LOCAL_IP_1=`cat /etc/hosts | grep \`hostname\` | awk '{print $1}'`
LOCAL_IP_2=$(cat /etc/hosts | grep $(hostname) | awk '{print $1}')
echo "\$LOCAL_IP_1=$LOCAL_IP_1, \$LOCAL_IP_2=$LOCAL_IP_2"
# 二者输出一致

arr1=(xx    xyz    "hello,      world"      1234   20.0    "你好")
echo "数组arr1的长度: ${#arr1[@]}"    # 获取数组长度
echo "数组arr1的长度: ${#arr1[*]}"

echo "${#arr1}"   # 不写索引表示首元素，长度为2

len=${#arr1[@]}
last=`expr $len - 1` # 末元素的索引
echo "arr1的最后一个元素: ${arr1[$last]}"

# 另一种定义方式
arr2[0]=abc
arr2[1]=xyz
arr2[2]="世界，你好"
arr2[3]=1234
echo "arr2数组内容: ${arr2[@]}"
echo "数组arr2的长度: ${#arr2[@]}"

# 第一种方式
len_2=${#arr2[@]}
# last_2=`expr $len_2 - 1` 或
last_2=$((len_2-1))
for i in `seq 0 $last_2`
do
    # pos=`expr $i + 1` 或
    pos=$((i+1))   # 序号，令其从1开始
    echo "arr2中第${pos}个元素为: ${arr2[$i]}"
done

# 第二种方式
count=1
for ele in "${arr1[@]}" # 必须加引号，否则 hello world 拆成两个元素
do
    echo "arr1中第${count}个元素为: ${ele}"
    # count=`expr $count + 1` 或 count=$((count+1)) 或
    ((count++)) # 自增运算
done

# 定义
xyz() {
    echo "hello, function xyz!"
}
# 调用
xyz

xyz_with_params() {
    echo "函数传入参数个数为：$#"
    for i in `seq 1 $#`    
    do
        echo "第${i}个位置参数: $1"     
        shift   # 向左移动参数
    done
}
xyz_with_params abc xyz 123

xyz_with_return() {
    echo "设置返回值 1000"
    return 1000
}

xyz_with_return
echo "函数返回值: $?"   # 返回232

if xyz_with_return  # 注意该判断与其他语言中的区别
then
    echo "返回值零，成功"
else
    echo "返回值非零，失败"
fi

a=$(expr 3 + 2)
echo "a = $a"     # 5

b=$(expr $a + 10)
echo "b = $a + 10 = $b"     # 5 + 10 = 15

c=$(expr $a \* 10)
echo "c = $a * 10 = $c"     # 5 * 10 = 50

d=$(expr $a / 3)
echo "d = $a / 3 = $d"      # 5 / 3 = 1

e=$(expr $a % 3)
echo "e = $a % 3 = $e"      # 5 % 3 = 2

let "a += 10"
echo "a + 10 = $a"      # a + 10 = 15

let  "a /= 10"
echo "a / 10 = $a"      # a / 10 = 1

let "a++"
echo "a++ = $a"         # a++ = 2

let "b = $a + $b + $c"
echo "b = a + b + c = $b"   # a + b + c = 67

a=2
b=3
c=4
d=$((a + b * c))
echo $d   # 输出 14
((a++))
echo $a      # 输出 3
((b %= 2))
echo $b      # 输出 1    

echo "scale=3; 1.1 * 1.23" | bc    # 1.353

str1="hello world"
echo "原始字符串: $str1"
echo "字符串长度: ${#str1}"     # 11

str2="我是中文"
echo "中文字符串长度: ${#str2}" # 长度为4

echo "从第2个字符开始取字符串: ${str1:2}"   # llo world
echo "从第2个字符开始连续取3个字符: ${str1:2:3}"    # llo

echo "从开头删除最短匹配*o的子串: ${str1#*o}"   #  world

echo "从开头删除最长匹配*o的子串: ${str1##*o}"  # rld

echo "从末尾删除最短匹配o*的子串: ${str1%o*}"   # hello w

echo "从末尾删除最长匹配o*的子串: ${str1%%o*}"  # hell

${string/substring/replacement}
${string//substring/replacement}
${string/#substring/replacement}
${string/%substring/replacement}

str3="Hi World! Hello World! Hello Seres!"
echo ${str3/Hello/Goodbye}      # Hi World! Goodbye World! Hello Seres!
echo ${str3//Hello/Goodbye}     # Hi World! Goodbye World! Goodbye Seres!
echo ${str3/#Hi/Goodbye}        # Goodbye World! Hello World! Hello Seres!
echo ${str3/%Seres!/China!}     # Hi World! Hello World! Hello China!

str4="123"
echo ${str4:-"abc"}     # 123
echo ${str5:-"abc"}     # abc

str6="123"
echo ${str6:+abc}       # abc
echo ${str7:+abc}       # 空串

str8="123"
echo ${str8:?abc}       # 123
echo ${str9:?abc}       # 返回 str9: abc 并终止

if [ condition ]
then
  # code to be executed if the condition is true
else
  # code to be executed if the condition is false
fi

for variable_name in item1 item2 ... itemN
do
    # command
done

array=(xx  abc  "hello,      world"   12)

for ((i = 0; i < 5; i++))
do
    echo "Iteration: $i"
done

while [ condition ]
do
    # command
done

until [ condition ]
do
    # command
done

exec 3> output.txt  # 将文件描述符3重定向到output.txt文件
echo "Hello, World!" >&3  # 将文本写入文件描述符3所关联的文件

echo -e "hello1\nhello2\nhello3" > input.txt
exec 4< input.txt  # 将文件描述符4重定向到input.txt文件
while read line
do
    echo "Line: $line"
done <&4   # 从文件描述符4读取行

exec 3>&-  # 关闭文件描述符3
exec 4<&-  # 关闭文件描述符4

#!/bin/bash

check_nginx() {
    ps -ef | grep "/usr/sbin/nginx" | grep -v grep > /dev/null
    return $?
}

while true
do
    if check_nginx
    then
        echo "nginx存在 休息2s"
        sleep 2
        continue
    fi
    echo "启动nginx..."
    systemctl start nginx
    sleep 2
    if check_nginx
    then
        echo "重新启动nginx成功"
        continue
    fi
    echo "nginx无法启动 请检查配置"
    break
done

#!/bin/bash

LOG_DIR=./logs
[ -d ${LOG_DIR} ] || mkdir ${LOG_DIR}
cd ${LOG_DIR}

# 写入压缩日志
log_out() {
    log_path="compress.log"
    echo $1 >> $log_path
}

# 每10秒生成日志文件
produce_log_file() {
    while true
    do
        host_count=$(($RANDOM % 7 + 2)) # 随机生成[2,8]之间的整数
        now_time=$(date "+%H%M%S")  # date命令的格式化
        declare -a host_arr
        for i in $(seq 0 $host_count)
        do
            host_arr[$i]="10.83.26.$(($i + 10))"
        done

        for host in "${host_arr[@]}"
        do
            echo "生成日志文件：${host}_${now_time}.access.log"
            touch ${host}_${now_time}.access.log
        done
        sleep 10
    done
}

# 压缩日志文件
compress_log_file() {
    while true
    do
        sleep 1
        compress_time=$(find . -name "*.access.log" -exec basename {} \; | awk -F _ '{print $2}' | awk -F . '{print $1}' | sort -r | uniq | awk 'NR==1{print}')
        if [ -z "$compress_time" ]
        then
            log_out "当前没有日志文件要压缩"
            continue
        fi
        log_out "压缩 ${compress_time} 文件..."
        tar czf log_compress_${compress_time}.tar.gz $(find . -name "*${compress_time}.access.log")
        if [ $? -eq 0 ] && [ -e "log_compress_${compress_time}.tar.gz" ]
        then
            find . -name "*${compress_time}.access.log" -exec rm -f {} \;
        fi
        log_out "压缩 ${compress_time} 文件完成"
    done
}

produce_log_file &
compress_log_file &