70.for循環、while循環、break跳出循環、continue結束本次循環、exit
阿新 • • 發佈:2018-06-01
for while循環 break跳出循環 continue結束本次循環 exit退出整個腳本 for循環
語法:for 變量名 in 條件; do …; done
for 會以空格或者回車為分隔符
案例1
#!/bin/bash
sum=0
for i in `seq 1 100`
do
sum=$[$sum+$i]
echo $i
done
echo $sum
文件列表循環
#!/bin/bash
cd /etc/
for a in `ls /etc/`
do
if [ -d $a ]
then
ls -d $a
fi
done
while循環
語法 while 條件; do … ; done
- 案例1
#!/bin/bash while true do load=`w|head -1|awk -F ‘load average: ‘ ‘{print $2}‘|cut -d. -f1` if [ $load -gt 10 ] then /usr/lib/zabbix/alertscripts/mail.py [email protected] "load is high" "load is high: $load" fi sleep 30 done
- 案例2
#!/bin/bash while : do read -p "Please input a number: " n if [ -z "$n" ] then echo "you need input sth." continue fi n1=`echo $n|sed ‘s/[0-9]//g‘` if [ -n "$n1" ] then echo "you just only input numbers." continue fi break done echo $n
break跳出循環
#!/bin/bash
for i in `seq 1 5`
do
echo $i
if [ $i == 3 ]
then
break
fi
echo $i
done
echo aaaaaaa
continue結束本次循環?
忽略continue之下的代碼,直接進行下一次循環
#!/bin/bash
for i in `seq 1 5`
do
echo $i
if [ $i == 3 ]
then
continue
fi
echo $i
done
echo $i
exit直接退出腳本
#!/bin/bash
for i in `seq 1 5`
do
echo $i
if [ $i == 3 ]
then
exit
fi
echo $i
done
echo aaaaaaa
70.for循環、while循環、break跳出循環、continue結束本次循環、exit