See line breaks and carriage returns in editor

Question

To disagree with the official answer:

:set list will not show ^M characters (CRs). Supplying the -b option to vi/Vim will work. Or, once Vim is loaded, type :e ++ff=unix.

Assuming your vim settings for :set listchars=... is set to visualize the characters you are attempting to see, in this case the carriage return characters (typed with CTL + V, CTRM + M) —— otherwise, as reported in many of the comments on this answer, the ^M character will not show on :set list

:set list in Vim will show whitespace. End of lines show as '$' and carriage returns usually show as '^M'.

vi shows newlines (LF character, code x0A) by showing the subsequent text on the next line.

Use the -b switch for binary mode. For example , vi -b filename or vim -b filename --.

It will then show CR characters (x0D), which are not normally used in Unix style files, as the characters ^M.

Just to clarify why :set list won't show CR's as ^M without e ++ff=unix and why :set list has nothing to do with ^M's.

Internally when Vim reads a file into its buffer, it replaces all line-ending characters with its own representation (let's call it $'s). To determine what characters should be removed, it firstly detects in what format line endings are stored in a file. If there are only CRLF '\r\n' or only CR '\r' or only LF '\n' line-ending characters, then the 'fileformat' is set to dos, mac and unix respectively.

When list option is set, Vim displays $ character when the line break occurred no matter what fileformat option has been detected. It uses its own internal representation of line-breaks and that's what it displays.

Now when you write buffer to the disc, Vim inserts line-ending characters according to what fileformat options has been detected, essentially converting all those internal $'s with appropriate characters. If the fileformat happened to be unix then it will simply write \n in place of its internal line-break.

The trick is to force Vim to read a dos encoded file as unix one. The net effect is that it will remove all \n's leaving \r's untouched and display them as ^M's in your buffer. Setting :set list will additionally show internal line-endings as $. After all, you see ^M$ in place of dos encoded line-breaks.

Also notice that :set list has nothing to do with showing ^M's. You can check it by yourself (make sure you have disabled list option first) by inserting single CR using CTRL-V followed by Enter in insert mode. After writing buffer to disc and opening it again you will see ^M despite list option being set to 0.

You can find more about file formats on http://vim.wikia.com/wiki/File_format or by typing:help 'fileformat' in Vim.