What is `^M` and how do I get rid of it?

When I open the file in vim,I am seeing strange ^M characters.

Unfortunately,the world‘s favorite search engine does not do well with special characters in queries,so I‘m asking here:

• What is this ^M character?

• How could it have gotten there?

• How do I get rid of it?

he ^M is a carriage-return character. If you see this,you‘re probably looking at a file that originated in the DOS/Windows world,where an end-of-line is marked by a carriage return/newline pair,whereas in the Unix world,end-of-line is marked by a single newline.

A simpler way to do this is to use the following command:（需要安装该工具：yum install dos2unix）
dos2unix filename
This command works with path patterns as well,Eg
dos2unix path/name*
If it doesn‘t work,try using different mode:
dos2unix -c mac filename
-c Set conversion mode. Where CONVMODE is one of: ascii,7bit,iso,mac with ascii being the default.

?

其它方法：

:e ++ff=dos

The :e ++ff=dos command tells Vim to read the file again,forcing dos file format. Vim will remove CRLF and LF-only line endings,leaving only the text of each line in the buffer.

then

:set ff=unix

and finally

:wq