第二十三章 SHELL指令碼-CENTOS7.5知識
shell指令碼(三)
一. 使用if條件語句
案例:
#!/bin/bash
echo "===Check disk usage...==="
DISKU=df -h|awk '/vda1/{print $5}'|awk -F% '{print $1}'
if [ $DISKU -gt 10 ] ; then
echo "warning,Disk vda1 is over 90 usages....."
echo "warning,Disk vda1 is over 90 usages....."> /var/log/diskusage.log
else
echo "disk vda1 is normal.Good luck."
fi
1).根分割槽已用空間>80%則報警,否則不執行任何操作
#!/bin/bash
echo "===Check disk usage...==="
DISKU=df -h|awk '/vda1/{print $5}'|awk -F% '{print $1}'
if [ $DISKU -gt 10 ] ; then
echo "warning,Disk vda1 is over 90 usages....."
echo "warning,Disk vda1 is over 90 usages....."> /var/log/diskusage.log
else
echo "disk vda1 is normal.Good luck."
fi
2).判斷/tmp目錄下是否有win目錄,若不存在則建立目錄,存在不執行任何操作
#!/bin/bash
if [ ! -e /tmp/win ] ;then
echo "To create dir win"
mkdir /tmp/win
elif [ -f /tmp/win ] ;then
echo "To del win file"
rm -rf /tmp/win
echo "To create dir win"
mkdir /tmp/win
else
echo "此目錄win已經存在了。"
fi
3).判斷httpd是否已經啟動,若已啟動,則提示已執行,否則啟動httpd服務
Systemctl status httpd
If [ $? -eq 0 ]
Then
Echo “Service httpd is running.”
Else
Systemctl start httpd
Fi
4).執行指令碼時指定IP,結果為ping該主機,若通,則顯示up,否則顯示down
#!/bin/bash
ping -c2 172.18.199.10&>> /dev/null
if [ $? -eq 0 ]
then
echo "The IP $1 is up."
else
echo "The IP $1 is down."
fi
示例:
指令碼可互動輸入分數,並判斷分數在90-100之間,判斷為優秀,60-89之間為合格,59-40以下其他為不及格努力;39以下復讀,其它輸入為非法輸入。
#!/bin/bash
echo "=======Test========"
read -p "請輸入你的成績" Source
if [ $Source -gt 100 ] ; then
echo "輸入錯誤"
elif [ $Source -lt 0 ] ; then
echo "輸入錯誤"
elif [ $Source -ge 90 ] ; then
echo "優秀"
elif [ $Source -ge 60 ] ; then
echo "及格"
elif [ $Source -ge 40 ] ; then
echo "努力"
else
echo "復讀";
fi
二、迴圈語句:
1、FOR迴圈寫法
for((i=1;i<=10;i++));
for i in `seq 10`
for i in {1..10}
#!/bin/bash
for i in {1..10}
do
echo “$i”
done
#!/bin/bash
for i in $*
Do
Echo “$i”
Done
do
echo $i
done
vim num.txt
#!/bin/bash
for i in `cat num.txt`
Do
Echo “$i”
Done
#!/bin/bash
ipnet='172.18.11.'
for IPaddress in {1..254}
do
ping -c 1 $ipnet$IPaddress &> /dev/null
if [ $? -eq 0 ] ; then
echo "This host $ipnet$IPaddress is up."
echo "This host $ipnet$IPaddress is up." >> /tmp/ping-18net.log
else
echo "This host $ipnet$IPaddress is down."
fi
done
echo "Net18 ping ok."
#!/bin/bash
for (( i = 1; i <=9; i++ ))
do
for (( j=1; j <= i; j++ ))
do
let "chengji = i * j"
echo -n "$i*$j=$chengji "
done
echo ""
done
2、while迴圈寫法
如:
i=1
while [ $i -lt 10 ]
do
echo $i
let i++
done
i++ 等同於 i=i+1
i+=1 等同於 i=i+1
i+=2 i=i+2
i-- i=i-1
i-=2 i=i-2
i*=2 i=i*2
迴圈結構中數值增量需要與let合作,如let i++
作業:用指令碼完成
1.公司要求新進一批實習生,要為他們建立使用者名稱shixi01 ---- shixi10,要求所有人的密碼初始都為great123。
2.用FOR迴圈寫九九乘法表。
3.用for及while結構分別完成掃描本網段址的指令碼