VIM's Hidden Newline

At some point in your daily life with the ubiquitous development environment VIM, you might face an advanced data structure called text file, an integral part of an enterprise database system called filesystem. And as you start to play with newlines you might wonder why the following is:

$ vim vim-file
$ echo -n "echo-line" > echo-file
$ cat echo-file vim-file
echo-linevim-line
$ cat vim-file echo-file
vim-line
echo-line$

echo produces no newline as expected, but VIM does. Although the file just contains the content

vim-line
~

with no explicit newline, cat still prints one. And indeed there is one as the hex dump shows:

$ xxd vim 
0000000: 7669 6d0a                                vim.

The final dot after the characters vim shows it. In my case it was not that obvious what files originated from VIM and which did not. Unfortunately you do not see a difference between the two files in less, and VIM will only give a hint when the final newline is missing and automatically correct in when writing the file. But in the main display it is hidden.

To avoid the final newline, VIM knows the binary and eol options that can be used together to prevent VIM from writing the final newline. But be advised that in general you are safer when using it in Unix text files.

Maybe one day we might get past these teething troubles and start spending our hacking time on some user-friendly systems. But since the computer revolution has not happened yet I guess we just have to wait a little longer.

P.S. It is a shame I could not make any link to ZFS this time. So be it! For this post ...