day 9

发布时间：2020-12-15 23:06:25 所属栏目：安全来源：网络整理

导读：while 循环语法： while 条件；do ...；done ^C [[email?protected] shell]# vim while.sh #!/bin/bash while : do ? load=`w | head -1 | awk -F ‘load average:‘ ‘{print $2}‘ | cut -d . -f1 | sed ‘s/ //‘` ? if [ $load -gt 10 ] ? then ????? e

while 循环

语法：

　　while 条件；do ...；done

^C [[email?protected] shell]# vim while.sh

#!/bin/bash

while :

do ?

load=`w | head -1 | awk -F ‘load average:‘ ‘{print $2}‘ | cut -d . -f1 | sed ‘s/ //‘` ?

　　if [ $load -gt 10 ] ?

　　then ?????

　　　　echo $load ?

done

~?????????????????????

^C [[email?protected] shell]# vim while2.sh

#!/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

continue 重复该循环

break　跳出循环

[[email?protected] shell]# vim break.sh
[[email?protected] shell]# sh -x break.sh
++ seq 1 5
+ for i in ‘`seq 1 5`‘
+ echo 1
1
+ ‘[‘ 1 -eq 3 ‘]‘
+ for i in ‘`seq 1 5`‘
+ echo 2
2
+ ‘[‘ 2 -eq 3 ‘]‘
+ for i in ‘`seq 1 5`‘
+ echo 3
3
+ ‘[‘ 3 -eq 3 ‘]‘
+ break
+ echo ok
ok
[[email?protected] shell]#

（编辑：李大同）

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