Understanding ed will let you understand all that feels strange about the system. It set the standards for sed and vi.

ed was designed for real terminals, i.e. a typewriter. You would type a command to the computer, and it would type out any errors. It would not waste paper, ink, and time by typing out COMMAND RUN SUCCESSFULLY after each command. A silent machine meant a happy machine.

To fully appreciate ed, you should [slow down your terminal].

Basic Usage

Open a file:

1ed file.md

Insert a new line.

1. Press i<Return>
2. Type the line.
3. Finish your edit with single dot.

i
dear diary,
.

Print the current line:

p

Change the current line:

c
Dear diary,
.

Delete the current line:

d

Write the 'buffer' to disk:

w

Quit:

q

Working with Lines

Open that file:

ed file.md

Add a line:

a
Fortune of the day:
.

Run fortune, and place the results inside the current buffer:

r!fortune
?

The ? indicates an error. We can ask what the error was with the command h:

r!fortune
?
h
Unexpected command suffix

The command r has something after it which makes no sense. It should have a space after the r!

r !fortune
42

That last line means ed has 42 characters in its buffer.

Read the current line, and show the line number:

n
2	How many weeks are there in a light year?

This means we are on line 2.

Fill up the file with fortunes:

r !for x in 1 2 3 ; do echo --- && fortune ; done

Print out which line in the file we are currently on:

=
12

There are twelve lines. Go back up to line 3:

3
---

So line 3 just has our delimiter: ---.

Whenever you hit enter, ed prints the current line then moves to the next line.

I would have promised those terrorists a trip to Disneyland if it would have

gotten the hostages released.  I thank God they were satisfied with the

missiles and we didn't have to go to that extreme.

Go back a few lines:

-3

Print out 'current line', using the dot:

.

Print current line with the number of that line:

.n
11	Possessions increase to fill the space available for their storage.

Print and number the next three lines:

.,+3n
9	You have no real enemies.
10	------
11	Possessions increase to fill the space available for their storage.

Skip ahead four lines:

+4
?
h
Invalid address

This is an invalid address because there are no more lines, so ed cannot print them.

All Commands

Meta Commands

Create

Read

Update

Delete