write guide to ed

writing/ed.md

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+---
+title: "Ed: The Standard Editor"
+tags: [ "writing", "guide" ]
+---
+
+`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.
+
+# Basic Usage
+
+Open a file:
+
+```sh
+ed file.md
+```
+
+Insert a new line.
+
+1. Press `i<Return>`
+1. Type the line.
+1. Finish your edit with single dot.
+
+
+```ed
+i
+dear diary,
+.
+```
+
+Print the current line:
+
+```ed
+p
+```
+
+Change the current line:
+
+```ed
+c
+Dear diary,
+.
+```
+
+Delete the current line:
+
+
+```ed
+d
+```
+
+
+
+Write the 'buffer' to disk:
+
+
+```ed
+w
+```
+
+Quit:
+
+```ed
+q
+```
+
+# Working with Lines
+
+Open that file:
+
+
+```ed
+ed file.md
+```
+
+Add a line:
+
+```ed
+a
+Fortune of the day:
+.
+```
+
+Run `fortune`, and place the results inside the current buffer:
+
+```ed
+r!fortune
+?
+```
+
+The `?` indicates an error.  We can ask what the error was with the command
+`h`:
+
+```ed
+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`!
+
+
+```ed
+r !fortune
+42
+```
+
+That last line means `ed` has 42 characters in its buffer.
+
+Read the current line, and show the line number:
+
+
+```ed
+n
+2	How many weeks are there in a light year?
+```
+
+This means we are on line 2.
+
+Fill up the file with fortunes:
+
+```ed
+r !for x in 1 2 3 ; do echo --- && fortune ; done
+```
+
+Print out which line in the file we are currently on:
+
+```ed
+=
+12
+```
+
+There are twelve lines.  Go back up to line 3:
+
+```ed
+3
+---
+```
+
+So line 3 just has our delimiter: `---`.
+
+Whenever you hit enter, `ed` prints the current line then moves to the next
+line.
+
+
+```ed
+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:
+
+```ed
+-3
+```
+
+Print out 'current line', using the dot:
+
+
+```ed
+.
+```
+
+Print current line with the number of that line:
+
+
+```ed
+.n
+11	Possessions increase to fill the space available for their storage.
+```
+
+Print and number the next three lines:
+
+
+```ed
+.,+3n
+9	You have no real enemies.
+10	------
+11	Possessions increase to fill the space available for their storage.
+```
+
+Skip ahead four lines:
+
+```ed
++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`    |