261 lines
5.4 KiB
Markdown
261 lines
5.4 KiB
Markdown
---
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title: "Ed: The Standard Editor"
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tags: [ "writing", "guide" ]
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---
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`ed` was designed for real terminals, i.e. a typewriter.
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You would type a command to the computer, and it would type out any errors.
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It would not waste paper, ink, and time by typing out `COMMAND RUN SUCCESSFULLY` after each command.
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A silent machine meant a happy machine.
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# Basic Usage
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Open a file:
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```sh
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ed file.md
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```
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Insert a new line.
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1. Press `i<Return>`
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1. Type the line.
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1. Finish your edit with single dot.
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```ed
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i
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dear diary,
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.
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```
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Print the current line:
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```ed
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p
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```
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Change the current line:
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```ed
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c
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Dear diary,
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.
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```
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Delete the current line:
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```ed
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d
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```
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Write the 'buffer' to disk:
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```ed
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w
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```
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Quit:
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```ed
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q
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```
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# Working with Lines
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Open that file:
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```ed
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ed file.md
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```
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Add a line:
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```ed
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a
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Fortune of the day:
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.
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```
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Run `fortune`, and place the results inside the current buffer:
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```ed
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r!fortune
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?
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```
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The `?` indicates an error. We can ask what the error was with the command
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`h`:
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```ed
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r!fortune
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?
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h
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Unexpected command suffix
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```
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The command `r` has something after it which makes no sense. It should have a
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space after the `r`!
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```ed
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r !fortune
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42
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```
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That last line means `ed` has 42 characters in its buffer.
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Read the current line, and show the line number:
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```ed
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n
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2 How many weeks are there in a light year?
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```
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This means we are on line 2.
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Fill up the file with fortunes:
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```ed
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r !for x in 1 2 3 ; do echo --- && fortune ; done
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```
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Print out which line in the file we are currently on:
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```ed
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=
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12
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```
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There are twelve lines. Go back up to line 3:
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```ed
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3
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---
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```
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So line 3 just has our delimiter: `---`.
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Whenever you hit enter, `ed` prints the current line then moves to the next
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line.
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```ed
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I would have promised those terrorists a trip to Disneyland if it would have
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gotten the hostages released. I thank God they were satisfied with the
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missiles and we didn't have to go to that extreme.
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```
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Go back a few lines:
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```ed
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-3
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```
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Print out 'current line', using the dot:
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```ed
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.
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```
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Print current line with the number of that line:
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```ed
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.n
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11 Possessions increase to fill the space available for their storage.
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```
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Print and number the next three lines:
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```ed
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.,+3n
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9 You have no real enemies.
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10 ------
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11 Possessions increase to fill the space available for their storage.
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```
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Skip ahead four lines:
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```ed
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+4
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?
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h
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Invalid address
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```
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This is an `invalid address` because there are no more lines, so `ed` cannot print them.
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# All Commands
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Meta Commands
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-------------
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| Aim | Command |
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|:------------------------------------------------|:---------------:|
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| Explain an error (`?`) | `h` |
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| Show a prompt when `ed` can take a command. | `P` |
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| Change the default filename to `rec.txt`. | `f rec.txt` |
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| Save the file. | `w` |
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| Append a line after line 8. | `8a` |
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| Move three lines down. | `+3` |
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| Move four lines back. | `-4` |
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| Move to the last line. | `$` |
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Create
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------
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| Aim | Command |
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|:--------------------------------------------------------------------|:---------------:|
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| Insert a line before line 5. | `5i` |
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| Append a line after line 8. | `8a` |
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| Read all of `~/.profile` into the current position. | `r ~/.profile` |
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| Run `dir` and place the results into the current position. | `r !dir` |
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| Copy lines 10 to 15 to line 23. | `10,15t23` |
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Read
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------
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| Aim | Command |
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|:--------------------------------------------------------|:--------------:|
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| Print current line. | `.` or `p` |
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| Read lines 1 to 10. | `1,10p` |
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| Print and number lines 2 to 7. | 2,7n |
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| Find the next line ending with `fi` | /fi$/n |
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| Show the number of the next line starting with `if`. | `/^if/=` |
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| Find the line which contains `HOME`. | `?HOME?` |
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| Print the next five lines literally (showing tabs). | `.,+5l` |
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| Print from here till the end of the file. | `.,$p` |
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| Show all lines with `HOME` and show their numbers. | `g/HOME/n` |
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Update
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------
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| Aim | Command |
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|:------------------------------------------------|:------------------------:|
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| On line 30, substitute `less` with `less -R` | `30s/less/less -R/` |
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| Change each line starting `#` to `##` | `,s^# /## /g` |
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| Move lines 50 to 55 to line 20. | `50,55m20` |
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Delete
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------
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| Aim | Command |
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|:------------------------------------------------|:-----------:|
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| Delete line 4. | `4d` |
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| Delete from here to four lines down. | `.,+4d |
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| Delete all lines starting with `#`. | `g/^#/d` |
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