第一類：數字性迴圈
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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

-----------------------------
for1-3.sh

#!/bin/bash

for i in {1..10}
do
echo $(expr $i \* 3 + 1);
done
 

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for1-4.sh

#!/bin/bash

awk 'BEGIN{for(i=1; i<=10; i++) print i}'

第二類：字元性迴圈
-----------------------------
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
 

-----------------------------
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

第三類：路徑查詢
-----------------------------
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