sed removes newline at EOF

Question

I've tried using sed to replace an SELECT with BELECT in a file:

sed 's/SELECT/BELECT/g' add_pixel.sql | diff - add_pixel.sql

Gives me:

22c22
<   BELECT MAX(ID) INTO max_id FROM pixels;
---
>   SELECT MAX(ID) INTO max_id FROM pixels;
36c36
<       '(BELECT id FROM pixels WHERE pixel_id=''', new_pixel_id,
---
>       '(SELECT id FROM pixels WHERE pixel_id=''', new_pixel_id,
47c47
< DELIMITER ;
---
> DELIMITER ;
\ No newline at end of file

This was confirmed by wc - the fiel after sed is one line shorter than the original.

Why did sed's 's/SELECT/BELECT/g' removed the newline from the last line of the file?

Answer 1

It's your sql file that's missing the newline. sed was "nice" and made sure its output had a trailing newline.

$ diff <(printf 'x') <(printf 'x\n')
1c1
< x
\ No newline at end of file
---
> x

$ diff <(printf 'x\n') <(printf 'x')
1c1
< x
---
> x
\ No newline at end of file

Notice how the "\ No newline..."-line is positioned according to which file was missing it.