第一类：数字性循环
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for1-1.sh
#!/bin/bash for((i=1;i<=10;i++)); do echo $(expr $i \* 3 + 1); done
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for1-2.sh
#!/bin/bash for i in $(seq 1 10) do echo $(expr $i \* 3 + 1); done
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for1-3.sh
#!/bin/bash for i in {1..10} do echo $(expr $i \* 3 + 1); done-----------------------------
for1-4.sh
#!/bin/bash awk 'BEGIN{for(i=1; i<=10; i++) print i}'第二类：字符性循环
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for2-1.sh
#!/bin/bash for i in `ls`; do echo $i is file name\! ; done
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for2-2.sh
#!/bin/bash for i in $* ; do echo $i is input chart\! ; done
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for2-3.sh
#!/bin/bash for i in f1 f2 f3 ; do echo $i is appoint ; done
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for2-4.sh
#!/bin/bash list="rootfs usr data data2" for i in $list; do echo $i is appoint ; done
第三类：路径查找
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for3-1.sh
#!/bin/bash for file in /proc/*; do echo $file is file path \! ; done
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for3-2.sh
#!/bin/bash for file in $(ls *.sh) do echo $file is file path \! ; done
总结：
现在一般都使用for in结构，for in结构后面可以使用函数来构造范围，比如$()、``这些，里面写一些查找的语法，比如ls test*，那么遍历之后就是输出文件名了。
第一类：数字性循环
-----------------------------
for1-1.sh
#!/bin/bash for((i=1;i<=10;i++)); do echo $(expr $i \* 3 + 1); done
-----------------------------
for1-2.sh
#!/bin/bash for i in $(seq 1 10) do echo $(expr $i \* 3 + 1); done
-----------------------------
for1-3.sh
#!/bin/bash for i in {1..10} do echo $(expr $i \* 3 + 1); done-----------------------------
for1-4.sh
#!/bin/bash awk 'BEGIN{for(i=1; i<=10; i++) print i}'第二类：字符性循环
-----------------------------
for2-1.sh
#!/bin/bash for i in `ls`; do echo $i is file name\! ; done
-----------------------------
for2-2.sh
#!/bin/bash for i in $* ; do echo $i is input chart\! ; done
-----------------------------
for2-3.sh
#!/bin/bash for i in f1 f2 f3 ; do echo $i is appoint ; done
-----------------------------
for2-4.sh
#!/bin/bash list="rootfs usr data data2" for i in $list; do echo $i is appoint ; done
第三类：路径查找
-----------------------------
for3-1.sh
#!/bin/bash for file in /proc/*; do echo $file is file path \! ; done
-----------------------------
for3-2.sh
#!/bin/bash for file in $(ls *.sh) do echo $file is file path \! ; done
总结：
现在一般都使用for in结构，for in结构后面可以使用函数来构造范围，比如$()、``这些，里面写一些查找的语法，比如ls test*，那么遍历之后就是输出文件名了。
