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

Question

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?
• How could it have got there?
• How do I get rid of it?

Answer 1

The ^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.

Read this article for more detail, and also the Wikipedia entry for newline.

This article discusses how to set up vim to transparently edit files with different end-of-line markers.

If you have a file with ^M at the end of some lines and you want to get rid of them, use this in Vim:

:s/^M$//

(Press Ctrl+V Ctrl+M to insert that ^M.)

Answer 2

Most UNIX operating systems have a utility called dos2unix that will convert the CRLF to LF. The other answers cover the "what are they" question.

Answer 3

You can clean this up with sed:

sed -e 's/^M$//' < infile > outfile

The trick is how to enter the carriage-return properly. Generally, you need to type C-v C-m to enter a literal carriage return. You can also have sed work in place with

sed -i.bak -e 's/^M$//' infile

Answer 4

Another way to get rid of stupid chars is with the tr command.

I have a small script that look like this

#!/bin/sh
cat $1 | tr -d '\r' > ~/.tmp_file.txt
mv ~/.tmp_file.txt $1

Answer 5

A simpler way to do this is to use the following command:

dos2unix   filename