shell编程--while循环

脚本

[root@lynn-04 shell]# vim while2.sh

#!/bin/bash
i=6
while [ $i -gt 0 ]
do
    i=$[$i-1]
    echo $i
done

执行结果

[root@lynn-04 shell]# sh while2.sh
5
4
3
2
1
0

脚本

[root@lynn-04 shell]# vim while1.sh

#!/bin/bash
load=`w|head -1|awk -F 'load average: ' '{print $2}'|cut -d. -f1`
while [ $load -lt 10 ]
do
    echo $load
    /usr/lib/zabbix/alertscripts/mail.py 15******[e-mail] "load high" "$load"
    exit
done

执行结果 这里是发邮件的脚本 当然我的邮箱也会收到报警邮件

[root@lynn-04 shell]# sh while1.sh
0

9*9乘法口诀 脚本

[root@lynn-04 shell]# vim 99.sh

#!/bin/bash
echo "9*9======"
i=1
j=1
line=""
while [[ i -lt 10 ]];
do
j=1
line=""
until [[ j -eq 10 ]];    #until和while相反，表示条件不满足执行循环
do
      if [[ j -le i ]];
      then
          result=$(expr $i \* $j)
          resultStr="$j X $i = $result"
          line=${line}${resultStr}"\t"
      fi
j=$(expr $j + 1)
done
    echo -e ${line}
    i=$(expr $i + 1)
done
echo "9*9======"

执行结果

[root@lynn-04 shell]# sh 99.sh
9*9======
1 X 1 = 1	
1 X 2 = 2	2 X 2 = 4	
1 X 3 = 3	2 X 3 = 6	3 X 3 = 9	
1 X 4 = 4	2 X 4 = 8	3 X 4 = 12	4 X 4 = 16	
1 X 5 = 5	2 X 5 = 10	3 X 5 = 15	4 X 5 = 20	5 X 5 = 25	
1 X 6 = 6	2 X 6 = 12	3 X 6 = 18	4 X 6 = 24	5 X 6 = 30	6 X 6 = 36	
1 X 7 = 7	2 X 7 = 14	3 X 7 = 21	4 X 7 = 28	5 X 7 = 35	6 X 7 = 42	7 X 7 = 49	
1 X 8 = 8	2 X 8 = 16	3 X 8 = 24	4 X 8 = 32	5 X 8 = 40	6 X 8 = 48	7 X 8 = 56	8 X 8 = 64	
1 X 9 = 9	2 X 9 = 18	3 X 9 = 27	4 X 9 = 36	5 X 9 = 45	6 X 9 = 54	7 X 9 = 63	8 X 9 = 72	9 X 9 = 81	
9*9======