What does ^M character mean in Vim?

To translate the new line instead of removing it:

:%s/\r/\r/g

Unix uses 0xA for a newline character. Windows uses a combination of two characters: 0xD 0xA. 0xD is the carriage return character. ^M happens to be the way vim displays 0xD (0x0D = 13, M is the 13th letter in the English alphabet).

You can remove all the ^M characters by running the following:

:%s/^M//g

Where ^M is entered by holding down Ctrl and typing v followed by m, and then releasing Ctrl. This is sometimes abbreviated as ^V^M, but note that you must enter it as described in the previous sentence, rather than typing it out literally.

This expression will replace all occurrences of ^M with the empty string (i.e. nothing). I use this to get rid of ^M in files copied from Windows to Unix (Solaris, Linux, OSX).

It probably means you've got carriage returns (different operating systems use different ways of signaling the end of line).

Use dos2unix to fix the files or set the fileformats in vim:

set ffs=unix,dos

:%s/\r//g 

worked for me today. But my situation may have been slightly different.