How to find out line-endings in a text file?

In the bash shell, try cat -v <filename>. This should display carriage-returns for windows files.

(This worked for me in rxvt via Cygwin on Windows XP).

^{Editor's note: cat -v visualizes \r (CR) chars. as ^M. Thus, line-ending \r\n sequences will display as ^M at the end of each output line. cat -e will additionally visualize \n, namely as $. (cat -et will additionally visualize tab chars. as ^I.)}

Ubuntu 14.04:

simple cat -e <filename> works just fine.

This displays Unix line endings (\n or LF) as $ and Windows line endings (\r\n or CRLF) as ^M$.

You can use the file utility to give you an indication of the type of line endings.

Unix:

$ file testfile1.txt
testfile.txt: ASCII text

"DOS":

$ file testfile2.txt
testfile2.txt: ASCII text, with CRLF line terminators

To convert from "DOS" to Unix:

$ dos2unix testfile2.txt

To convert from Unix to "DOS":

$ unix2dos testfile1.txt

Converting an already converted file has no effect so it's safe to run blindly (i.e. without testing the format first) although the usual disclaimers apply, as always.

In vi...

:set list to see line-endings.

:set nolist to go back to normal.

While I don't think you can see \n or \r\n in vi, you can see which type of file it is (UNIX, DOS, etc.) to infer which line endings it has...

:set ff

Alternatively, from bash you can use od -t c <filename> or just od -c <filename> to display the returns.