lk/writing/ed.md

title, tags

title	tags
Ed: The Standard Editor	writing guide sed vim

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:

ed 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

Aim	Command
Explain an error (?)	h
Show a prompt when ed can take a command.	P
Change the default filename to rec.txt.	f rec.txt
Save the file.	w
Append a line after line 8.	8a
Move three lines down.	+3
Move four lines back.	-4
Move to the last line.	$

Create

Aim	Command
Insert a line before line 5.	5i
Append a line after line 8.	8a
Read all of ~/.profile into the current position.	r ~/.profile
Run dir and place the results into the current position.	r !dir
Copy lines 10 to 15 to line 23.	10,15t23

Read

Aim	Command
Print current line.	. or p
Read lines 1 to 10.	1,10p
Print and number lines 2 to 7.	2,7n
Find the next line ending with fi	/fi$/n
Show the number of the next line starting with if.	/^if/=
Find the line which contains HOME.	?HOME?
Print the next five lines literally (showing tabs).	.,+5l
Print from here till the end of the file.	.,$p
Show all lines with HOME and show their numbers.	g/HOME/n

Update

Aim	Command
On line 30, substitute less with less -R	30s/less/less -R/
Change each line starting # to ##	,s^# /## /g
Move lines 50 to 55 to line 20.	50,55m20

Delete

Aim	Command
Delete line 4.	4d
Delete from here to four lines down.	`.,+4d
Delete all lines starting with #.	g/^#/d