10個常用的shell腳本

注意事項

1）開頭加解釋器：#!/bin/bash

2）語法縮進，使用四個空格；多加註釋說明。

3）命名建議規則：變量名大寫、局部變量小寫，函數名小寫，名字體現出實際作用。

4）默認變量是全局的，在函數中變量local指定為局部變量，避免汙染其他作用域。

5）有兩個命令能幫助我調試腳本：set -e 遇到執行非0時退出腳本，set-x 打印執行過程。

6）寫腳本一定先測試再到生產上。

1 獲取隨機字符串或數字

獲取隨機8位字符串：

class="">方法1：
# echo $RANDOM |md5sum |cut -c 1-8
471b94f2
方法2：
# openssl rand -base64 4
vg3BEg==
方法3：
# cat /proc/sys/kernel/random/uuid |cut -c 1-8
ed9e032c

獲取隨機8位數字：

 class="">方法1： 

# echo $RANDOM |cksum |cut -c 1-8
23648321
方法2：
# openssl rand -base64 4 |cksum |cut -c 1-8
38571131
方法3：
# date +%N |cut -c 1-8
69024815

cksum：打印CRC效驗和統計字節

2 定義一個顏色輸出字符串函數

 class="">方法1：
function echo_color() {
 if [ $1 == "green" ]; then
 echo -e "\033[32;40m$2\033[0m"
 elif [ $1 == "red" ]; then
 echo -e "\033[31;40m$2\033[0m"
 fi
}
方法2：
function echo_color() {
 case $1 in
 green)
 echo -e "\033[32;40m$2\033[0m"
 ;;
 red)
 echo -e "\033[31;40m$2\033[0m" 
 ;;
 *) 
 echo "Example: echo_color red string"
 esac
}
使用方法：echo_color green "test"

function關鍵字定義一個函數，可加或不加。

3 批量創建用戶

 class="">#!/bin/bash
DATE=$(date +%F_%T)
USER_FILE=user.txt
echo_color(){
 if [ $1 == "green" ]; then
 echo -e "\033[32;40m$2\033[0m"
 elif [ $1 == "red" ]; then
 echo -e "\033[31;40m$2\033[0m"
 fi
}
# 如果用戶文件存在並且大小大於0就備份
if [ -s $USER_FILE ]; then
 mv $USER_FILE ${USER_FILE}-${DATE}.bak
 echo_color green "$USER_FILE exist, rename ${USER_FILE}-${DATE}.bak"
fi
echo -e "User\tPassword" >> $USER_FILE
echo "----------------" >> $USER_FILE
for USER in user{1..10}; do
 if ! id $USER &>/dev/null; then
 PASS=$(echo $RANDOM |md5sum |cut -c 1-8)
 useradd $USER
 echo $PASS |passwd --stdin $USER &>/dev/null
 echo -e "$USER\t$PASS" >> $USER_FILE
 echo "$USER User create successful."
 else
 echo_color red "$USER User already exists!"
 fi
done

4 檢查軟件包是否安裝

 class="">#!/bin/bash
if rpm -q sysstat &>/dev/null; then
 echo "sysstat is already installed."
else
 echo "sysstat is not installed!"
fi

5 檢查服務狀態

 class="">#!/bin/bash
PORT_C=$(ss -anu |grep -c 123)
PS_C=$(ps -ef |grep ntpd |grep -vc grep)
if [ $PORT_C -eq 0 -o $PS_C -eq 0 ]; then
 echo "內容" | mail -s "主題" [email protected]
fi

6 檢查主機存活狀態

方法1：將錯誤IP放到數組裡面判斷是否ping失敗三次

 class="">#!/bin/bash 
IP_LIST="192.168.18.1 192.168.1.1 192.168.18.2"
for IP in $IP_LIST; do
 NUM=1
 while [ $NUM -le 3 ]; do
 if ping -c 1 $IP > /dev/null; then
 echo "$IP Ping is successful."
 break
 else
 # echo "$IP Ping is failure $NUM"
 FAIL_COUNT[$NUM]=$IP
 let NUM++
 fi
 done
 if [ ${#FAIL_COUNT[*]} -eq 3 ];then
 echo "${FAIL_COUNT[1]} Ping is failure!"
 unset FAIL_COUNT[*]
 fi
done

方法2：將錯誤次數放到FAIL_COUNT變量裡面判斷是否ping失敗三次

 class="">#!/bin/bash 
IP_LIST="192.168.18.1 192.168.1.1 192.168.18.2"
for IP in $IP_LIST; do
 FAIL_COUNT=0
 for ((i=1;i<=3;i++)); do
 if ping -c 1 $IP >/dev/null; then
 echo "$IP Ping is successful." 

 break
 else
 # echo "$IP Ping is failure $i"
 let FAIL_COUNT++
 fi
 done
 if [ $FAIL_COUNT -eq 3 ]; then
 echo "$IP Ping is failure!"
 fi
done

方法3：利用for循環將ping通就跳出循環繼續，如果不跳出就會走到打印ping失敗

 class="">#!/bin/bash
ping_success_status() {
 if ping -c 1 $IP >/dev/null; then
 echo "$IP Ping is successful."
 continue
 fi
}
IP_LIST="192.168.18.1 192.168.1.1 192.168.18.2"
for IP in $IP_LIST; do
 ping_success_status
 ping_success_status
 ping_success_status
 echo "$IP Ping is failure!"
done

7 監控CPU、內存和硬盤利用率

1）CPU

藉助vmstat工具來分析CPU統計信息。

 class="">#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F '[ :]+' '/inet addr/{print $4}') # 只支持CentOS6
MAIL="[email protected]"
if ! which vmstat &>/dev/null; then
 echo "vmstat command no found, Please install procps package." 
 exit 1 

fi
US=$(vmstat |awk 'NR==3{print $13}')
SY=$(vmstat |awk 'NR==3{print $14}')
IDLE=$(vmstat |awk 'NR==3{print $15}')
WAIT=$(vmstat |awk 'NR==3{print $16}')
USE=$(($US+$SY))
if [ $USE -ge 50 ]; then
 echo "
 Date: $DATE
 Host: $IP
 Problem: CPU utilization $USE
 " | mail -s "CPU Monitor" $MAIL
fi

2）內存

 class="">#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F '[ :]+' '/inet addr/{print $4}') 
MAIL="[email protected]"
TOTAL=$(free -m |awk '/Mem/{print $2}')
USE=$(free -m |awk '/Mem/{print $3-$6-$7}')
FREE=$(($TOTAL-$USE))
# 內存小於1G發送報警郵件
if [ $FREE -lt 1024 ]; then
 echo "
 Date: $DATE
 Host: $IP
 Problem: Total=$TOTAL,Use=$USE,Free=$FREE
 " | mail -s "Memory Monitor" $MAIL
fi

3）硬盤

 class="">#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F '[ :]+' '/inet addr/{print $4}') 
MAIL="[email protected]"
TOTAL=$(fdisk -l |awk -F'[: ]+' 'BEGIN{OFS="="}/^Disk \/dev/{printf "%s=%sG,",$2,$3}')
PART_USE=$(df -h |awk 'BEGIN{OFS="="}/^\/dev/{print $1,int($5),$6}')
for i in $PART_USE; do
 PART=$(echo $i |cut -d"=" -f1)
 USE=$(echo $i |cut -d"=" -f2)
 MOUNT=$(echo $i |cut -d"=" -f3)
 if [ $USE -gt 80 ]; then
 echo "
 Date: $DATE 

 Host: $IP
 Total: $TOTAL
 Problem: $PART=$USE($MOUNT)
 " | mail -s "Disk Monitor" $MAIL
 fi
done
>

8 批量主機磁盤利用率監控

前提監控端和被監控端SSH免交互登錄或者密鑰登錄。

寫一個配置文件保存被監控主機SSH連接信息，文件內容格式：IP User Port

 class="">#!/bin/bash
HOST_INFO=host.info
for IP in $(awk '/^[^#]/{print $1}' $HOST_INFO); do
 USER=$(awk -v ip=$IP 'ip==$1{print $2}' $HOST_INFO)
 PORT=$(awk -v ip=$IP 'ip==$1{print $3}' $HOST_INFO)
 TMP_FILE=/tmp/disk.tmp
 ssh -p $PORT $USER@$IP 'df -h' > $TMP_FILE
 USE_RATE_LIST=$(awk 'BEGIN{OFS="="}/^\/dev/{print $1,int($5)}' $TMP_FILE)
 for USE_RATE in $USE_RATE_LIST; do
 PART_NAME=${USE_RATE%=*}
 USE_RATE=${USE_RATE#*=}
 if [ $USE_RATE -ge 80 ]; then
 echo "Warning: $PART_NAME Partition usage $USE_RATE%!"
 fi
 done
done

9 檢查網站可用性

1）檢查URL可用性

 class="">方法1：
check_url() { 

 HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" $1)
 if [ $HTTP_CODE -ne 200 ]; then
 echo "Warning: $1 Access failure!"
 fi
}
方法2：
check_url() {
if ! wget -T 10 --tries=1 --spider $1 >/dev/null 2>&1; then 
#-T超時時間，--tries嘗試1次，--spider爬蟲模式
 echo "Warning: $1 Access failure!"
 fi
}

使用方法：check_url www.baidu.com

2）判斷三次URL可用性

思路與上面檢查主機存活狀態一樣。

 class="">方法1：利用循環技巧，如果成功就跳出當前循環，否則執行到最後一行
#!/bin/bash 
check_url() {
 HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" $1)
 if [ $HTTP_CODE -eq 200 ]; then
 continue
 fi
}
URL_LIST="www.baidu.com www.agasgf.com"
for URL in $URL_LIST; do
 check_url $URL
 check_url $URL
 check_url $URL
 echo "Warning: $URL Access failure!"
done

 class="">方法2：錯誤次數保存到變量
#!/bin/bash 
URL_LIST="www.baidu.com www.agasgf.com"
for URL in $URL_LIST; do 

 FAIL_COUNT=0
 for ((i=1;i<=3;i++)); do
 HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" $URL)
 if [ $HTTP_CODE -ne 200 ]; then
 let FAIL_COUNT++
 else
 break
 fi
 done
 if [ $FAIL_COUNT -eq 3 ]; then
 echo "Warning: $URL Access failure!"
 fi
done

 class="">方法3：錯誤次數保存到數組
#!/bin/bash 
URL_LIST="www.baidu.com www.agasgf.com"
for URL in $URL_LIST; do
 NUM=1
 while [ $NUM -le 3 ]; do
 HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" $URL)
 if [ $HTTP_CODE -ne 200 ]; then
 FAIL_COUNT[$NUM]=$IP #創建數組，以$NUM下標，$IP元素
 let NUM++
 else
 break
 fi
 done
 if [ ${#FAIL_COUNT[*]} -eq 3 ]; then
 echo "Warning: $URL Access failure!"
 unset FAIL_COUNT[*] #清空數組
 fi
done

10 檢查MySQL主從同步狀態

 class="">#!/bin/bash 
USER=bak
PASSWD=123456
IO_SQL_STATUS=$(mysql -u$USER -p$PASSWD -e 'show slave status\G' |awk -F: '/Slave_.*_Running/{gsub(": ",":");print $0}') #gsub去除冒號後面的空格
for i in $IO_SQL_STATUS; do 

 THREAD_STATUS_NAME=${i%:*}
 THREAD_STATUS=${i#*:}
 if [ "$THREAD_STATUS" != "Yes" ]; then
 echo "Error: MySQL Master-Slave $THREAD_STATUS_NAME status is $THREAD_STATUS!"
 fi
done

本章寫的Shell腳本例子都比較實用，在面試題中也經常出現，希望大家參考著多動手寫寫，不要複製粘貼就拿來跑，這樣是學不會的！

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關鍵字: 技術 Bash 腳本語言