Fun tip #2: Display trailing spaces using ed

This second fun-tip article will explain how to display trailing spaces in a text file, using the ed(1) editor. ed has a special command for showing a dollar character at the end of each line, which mean that if the line has some spaces, the dollar character will spaced from the last visible line character.

$ echo ",pl" | ed some-file.txt
453
This second fun-tip article will explain how to display trailing$
spaces in a text file, using the$
[ed(1)$](https://man.openbsd.org/ed)
editor.$
ed has a special command for showing a dollar character at the end of$
each line, which mean that if the line has some spaces, the dollar$
character will spaced from the last visible line character.$
$
.Bd -literal -offset indent$
echo ",pl" | ed some-file.txt$

This is the output of the article file while I am writing it. As you can notice, there is no trailing space here.

The first number shown in the ed output is the file size, because ed starts at the end of the file and then, wait for commands.

If I use that very same command on a small text files with trailing spaces, the following result is expected:

49
this is full    $
of trailing  $
spaces      !    $

It is also possible to display line numbers using the “n” command instead of the “p” command. This would produce this result for my current article file:

1559
1       .Dd November 29, 2018$
2       .Dt "Show trailing spaces using ed"$
3       This second fun-tip article will explain how to display trailing$
4       spaces in a text file, using the$
5       .Lk https://man.openbsd.org/ed ed(1)$
6       editor.$
7       ed has a special command for showing a dollar character at the end of$
8       each line, which mean that if the line has some spaces, the dollar$
9       character will spaced from the last visible line character.$
10      $
11      .Bd -literal -offset indent$
12      echo ",pl" | ed some-file.txt$
13      453$
14      .Dd November 29, 2018
15      .Dt "Show trailing spaces using ed"
16      This second fun-tip article will explain how to display trailing
17      spaces in a text file, using the
18      .Lk https://man.openbsd.org/ed ed(1)
19      editor.
20      ed has a special command for showing a '\ character at the end of
21      each line, which mean that if the line has some spaces, the '\
22      character will spaced from the last visible line character.
23
24      \&.Bd \-literal \-offset indent
25      \echo ",pl" | ed some-file.txt
26      .Ed$
27      $
28      This is the output of the article file while I am writing it. As you$
29      can notice, there is no trailing space here.$
30      $
31      The first number shown in the ed output is the file size, because ed$
32      starts at the end of the file and then, wait for commands.$
33      $
34      If I use that very same command on a small text files with trailing$
35      spaces, the following result is expected:$
36      $
37      .Bd -literal -offset indent$
38      49$
39      this is full
40      of trailing
41      spaces      !
42      .Ed$
43      $
44      It is also possible to display line numbers using the "n" command$
45      instead of the "p" command.$
46      This would produce this result for my current article file:$
47      .Bd -literal -offset indent$

This shows my article file with each line numbered plus the position of the last character of each line, this is awesome!

I have to admit though that including my own article as example is blowing up my mind, especially as I am writing it using ed.