1. 程式人生 > >30個關於Shell指令碼的經典案例(上)

30個關於Shell指令碼的經典案例(上)

對於初學者而言,因為沒有實戰經驗,寫不出來Shell指令碼很正常,如果工作了幾年的運維老年還是寫不出來,那就是沒主動找需求,缺乏練習,缺乏經驗。針對以上問題,總結了30個生產環境中經典的Shell指令碼,通過這些需求案例,希望能幫助大家提升Shell編寫思路,掌握編寫技巧。

先了解下編寫Shell過程中注意事項:

開頭加直譯器:#!/bin/bash
語法縮排,使用四個空格;多加註釋說明。
命名建議規則:變數名大寫、區域性變數小寫,函式名小寫,名字體現出實際作用。
預設變數是全域性的,在函式中變數local指定為區域性變數,避免汙染其他作用域。
有兩個
命令
能幫助我除錯指令碼:set -e 遇到執行非0時退出指令碼,set-x 列印執行過程。 寫指令碼一定先測試再到生產上。

1、獲取隨機字串或數字

獲取隨機8位字串:
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:
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:列印CRC效驗和統計位元組

2、定義一個顏色輸出字串函式

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 "[32;40m$2[0m"
            ;;
        red)
            echo -e "[31;40m$2[0m" 
            ;;
        *) 
            echo "Example: echo_color red string"
    esac
}

使用方法:echo_color green "test"

function關鍵字定義一個函式,可加或不加。

3、批量建立使用者

#!/bin/bash
DATE=$(date +%F_%T)
USER_FILE=user.txt
echo_color(){
    if [ $1 == "green" ]; then
        echo -e "[32;40m$2[0m"
    elif [ $1 == "red" ]; then
        echo -e "[31;40m$2[0m"
    fi
}
# 如果使用者檔案存在並且大小大於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	Password" >> $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	$PASS" >> $USER_FILE
        echo "$USER User create successful."
    else
        echo_color red "$USER User already exists!"
    fi
done

4、檢查軟體包是否安裝

#!/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

#!/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
#!/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變數裡面判斷是否ping失敗三次
#!/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迴圈將ping通就跳出迴圈繼續,如果不跳出就會走到列印ping失敗
#!/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、記憶體和硬碟利用率

1)CPU
藉助vmstat工具來分析CPU統計資訊。

#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F  [ :]+   /inet addr/{print $4} )  # 只支援CentOS6
MAIL="[email protected]"
if ! which vmstat &>/dev/null; then
    echo "vmstat command no found, Please install procps package." 
    exit 1
fi
US=$(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)記憶體
#!/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))
# 記憶體小於1G傳送報警郵件
if [ $FREE -lt 1024 ]; then
    echo "
    Date: $DATE
    Host: $IP
    Problem: Total=$TOTAL,Use=$USE,Free=$FREE
    " | mail -s "Memory Monitor" $MAIL
fi

3)硬碟
#!/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、批量主機磁碟利用率監控

前提監控端和被監控端SSH免互動登入或者金鑰登入。

寫一個配置檔案儲存被監控主機SSH連線資訊,檔案內容格式:IP User Port

#!/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
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。

方法1:利用迴圈技巧,如果成功就跳出當前迴圈,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

   方法2:錯誤次數儲存到變數

#!/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

   方法3:錯誤次數儲存到陣列


#!/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]=$IP  #建立陣列,以$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[*]    #清空陣列
    fi
done

10、檢查MySQL主從同步狀態

#!/bin/bash  
USER=bak
PASSWD=123456
IO_SQL_STATUS=$(mysql -u$USER -p$PASSWD -e  show slave statusG  |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

動手練一練,讓你的Shell功底上升一個段位!