shell的循环主要有3种,for,while,until
shell的分支判断主要有2种,if,case
一,for循环
- #!/bin/bash
-
- for file in $(ls /tmp/test/mytest |grep sh)
- do
- echo $file
- done
-
- for ((i=0;i<10;i++))
- do
- echo -n $i
- done
-
- echo \
-
- for i in 0 1 2 3 4 5 6 7 8 9
- do
- echo -n $i
- done
-
- echo \
-
- for i in "0 1 2 3 4 5 6 7 8 9"
- do
- echo -n $i
- done
-
- exit 0
#!/bin/bash
for file in $(ls /tmp/test/mytest |grep sh) //for in格式是shell for的基本格式,根js的for in类似
do //循环开始你就把它当成{
echo $file
done //循环结束你就把它当成}
for ((i=0;i<10;i++)) //注意是双小括号,由于受其他语言的影响,很容易搞错
do
echo -n $i
done
echo \ //输出换行
for i in 0 1 2 3 4 5 6 7 8 9
do
echo -n $i
done
echo \
for i in "0 1 2 3 4 5 6 7 8 9" //这个根上面是有区别的,这个循环只循环了一次,双引号里面只是一个变量
do
echo -n $i
done
exit 0
二,while循环
- #!/bin/bash
- i=0
- while ((i<10))
- do
- echo $i
- ((i += 1))
- done
-
- i=0
- while [ $i -lt 10 ]
- do
- echo $i
- let "i+=1"
- done
- exit 0
#!/bin/bash
i=0
while ((i<10))
do
echo $i
((i += 1))
done
i=0
while [ $i -lt 10 ] //注意括号内侧二边的空格
do
echo $i
let "i+=1" //加1
done
exit 0
三,until循环
- #!/bin/bash
-
- END_CONDITION=end
- until [ "$var1" = "$END_CONDITION" ]
- do
- echo "Input variable #1 "
- echo "($END_CONDITION to exit)"
- read var1
- echo "variable #1 = $var1"
- echo
- done
- exit 0
#!/bin/bash
END_CONDITION=end
until [ "$var1" = "$END_CONDITION" ] //读取的变量根设定的变量相等时退出循环,不然永远循环
do
echo "Input variable #1 "
echo "($END_CONDITION to exit)"
read var1
echo "variable #1 = $var1"
echo
done
exit 0
四,if语句
- #!/bin/bash
-
- echo "Input a number #1 "
- read num
- echo "variable #1 = $num"
-
- if [ $num -lt 60 ]
- then
- echo "you are not pass"
- elif [ $num -lt 70 ] && [ $num -ge 60 ]
- then
- echo "pass"
- elif [[ $num -lt 85 && $num -ge 70 ]]
- then
- echo "good"
- elif (( $num <= 100 )) && (( $num >= 85 ))
- then
- echo "very good"
- else
- echo "num is wrong"
- fi
-
- exit 0
#!/bin/bash
echo "Input a number #1 "
read num
echo "variable #1 = $num"
if [ $num -lt 60 ] //注意lt前面的-,很容易忘的
then
echo "you are not pass"
elif [ $num -lt 70 ] && [ $num -ge 60 ] //多个条件的判断
then
echo "pass"
elif [[ $num -lt 85 && $num -ge 70 ]] //如果放在一起,要注意是双方括号,不要写成[ $num -lt 85 && $num -ge 70 ]
then
echo "good"
elif (( $num <= 100 )) && (( $num >= 85 )) //对于有语言基础的人来说,这种写法让人觉得很舒服,不要忘了是双小括号
then
echo "very good"
else
echo "num is wrong"
fi //if要有结束标签的,根XML很像,不闭合,就报错
exit 0
五,case语句
- #!/bin/sh
- case $1 in
- start)
- echo "start ok"
- ;;
- stop)
- echo "stop ok"
- ;;
- restart)
- echo "restart ok"
- ;;
- *)
- echo "no param"
- ;;
- esac
- exit 0
-
- [root@krlcgcms01 forif]# sh c1.sh stop
- stop ok
阅读(711) | 评论(0) | 转发(0) |