1.for循环
循环1-100的数字,并输出
for ((i=1;i<=100;i++))
do
echo $i
done
2.case 判断语句
接着上面的循环写,在10,20,30的时候划分割线
for ((i=1;i<=100;i++))
do
case $i in
10 )
echo "---------"
exit
;;
20 )
echo "---------"
exit
;;
30 )
echo "---------"
exit
;;
* )
echo "$i"
;;
esac
done
3.while 循环
在上面代码for循环改造成while循环
i=1
while [ $i -le 30 ]
do
case $i in
10 )
echo "---------"
exit
;;
20 )
echo "---------"
exit
;;
30 )
echo "---------"
exit
;;
* )
echo "$i"
;;
esac
let i=i+1
done
其中:let 用于执行表达式,变量计算中不需要加上 $ 来表示变量。如果表达式中包含了空格或其他特殊字符,则必须引起来。
4.select交互选择菜单
echo "please select menu number:"
select var in "a" "b" "c"
do
case $var in
a )
echo "selected a"
;;
b )
echo "selected b"
;;
c )
echo "selected c"
;;
esac
done
执行结果:
please select menu number:
1) a
2) b
3) c
selected a
selected b
selected c
选择时前面有“#?”,不太友好。用PS3(select交互提示值)调整下
PS3="please select menu number:"
select var in "a" "b" "c"
do
case $var in
a )
echo "selected a"
;;
b )
echo "selected b"
;;
c )
echo "selected c"
;;
esac
done
执行结果:
1) a
2) b
3) c
please select menu number:1
selected a
please select menu number:2
selected b
please select menu number:3
selected c
please select menu number:
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