假设读取的文件为当期目录下的 test.txt 文件，内容如下：
Google
Codercto
Taobao实例 1
#!/bin/bash
while read line
do
echo $line
done < test.txt
while read line
do
echo $line
done < test.txt
执行输出结果为：
Google
Codercto
Taobao实例 2
#!/bin/bash
cat test.txt | while read line
do
echo $line
done
cat test.txt | while read line
do
echo $line
done
执行输出结果为：
Google
Codercto
Taobao实例 3
for line in `cat test.txt`
do
echo $line
done
do
echo $line
done
执行输出结果为：
Google
Codercto
Taobaofor 逐行读和 while 逐行读是有区别的，如:
$ cat test.txt
Google
Codercto
Taobao
$ cat test.txt | while read line; do echo $line; done
Google
Codercto
Taobao
$ for line in $(<test.txt); do echo $line; done
Google
Codercto
Taobao
Codercto
Taobao
$ cat test.txt | while read line; do echo $line; done
Codercto
Taobao
$ for line in $(<test.txt); do echo $line; done
Codercto
Taobao
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