写法一：
----------------------------------------------------------------------------
#!/bin/bash

while read line
do
    echo $line
done < file(待读取的文件)
----------------------------------------------------------------------------

写法二：
----------------------------------------------------------------------------
#!/bin/bash

cat file(待读取的文件) | while read line
do
    echo $line
done
----------------------------------------------------------------------------

写法三：
----------------------------------------------------------------------------
for line in `cat file(待读取的文件)`
do
    echo $line
done
----------------------------------------------------------------------------

说明：
for逐行读和while逐行读是有区别的,如:
$ cat file
aaaa
bbbb
cccc dddd

$ cat file | while read line; do echo $line; done
aaaa
bbbb
cccc dddd

$ for line in $(<file); do echo $line; done
aaaa
bbbb
cccc
dddd