I occasionally open a file with vim and see something like this:

"<file name>" [Incomplete last line][dos format] 71 lines, 2912 characters

I understand all of that information except Incomplete last line. I realize this just means that there isn't a line termination character on the last line, and I know if I resave the file and reopen it, that message goes away, which implies that vim automatically adds the line termination character if it isn't already present. My question is: why does this matter, and why does vim bother to tell me about it?

1 Answer 1


The Unix convention is that a line is a sequence of zero or more characters ending with a newline character. A text file is a sequence of such lines. This is just a convention, but adhering to that convention allows text-processing tools to work together. It avoids problems of ambiguity in commands such as cat foo bar when the last character of foo is not a newline.

A sequence of characters that does not end with a newline is not a "line", in this sense. It is incomplete and some tools will not process it as the user might expect. Vim warns you about it because it is a potential problem and fixes it because Vim attempts to write proper files.

  • 1
    git also warns about it. Mar 3, 2017 at 18:59
  • Alright, that logic does actually make sense to me. I hadn't thought about it that way. Thanks!
    – pattivacek
    Mar 3, 2017 at 21:35

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