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)
expr $i * 3 + 1
done
输出：
4
7
10
13
16
19
22
25
28
31
for1-2.sh
#!/bin/bash
for i in $(seq 1 10)
do
#echo $(expr $i * 3 + 1)
expr $i * 3 + 1
done
for1-3.sh
#!/bin/bash
for i in {1..10}
do
expr $i * 3 + 1
done
for1-4.sh
#!/bin/bash
awk 'BEGIN{for(i=1;i<=10;i++) print i*3+1}'
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 the file name!
done
for2-3.sh
#!/bin/bash
for i in f1 f2 f3
do
echo $i is input arguments!
done
for2-4.sh
#!/bin/bash
list="boot usr tmp opt"
for i in $list
do
echo $i is appointed!
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 f in $(ls *.sh)
do
echo $f is file path !
done