The Ed Editor by Ken Thompson (Complete Series)

An editor developed by Bill Joy in 1976.
It was based on a program called em,
which in turn was an improvement of ed
itself developed by Ken Thompson,
one of the authors of Unix.
Ex is a simple but useful text editor
which itself later became the basis of Vi
which is not to be confused with Vim.
Original Vi was written in 1976
Vim, was only a much later development,
released first in 1991.
But back to ex which is the focus of this video.
ex is a very simple editor helpful for
configuring system files.
Its strange style arose from limitations
imposed by computing at the time.
This is how it works.

• starting up ex
  
• Lines are not automatically shown at startup
  
• set line numbers
  
• navigation: beginning/end of file 0/$
  
• Go to a specific line
  
• to copy or move
  
• to append text
  
• to save and quit
  
• find /word
  
• to substitute
  
• the origin of grep g/re/p
  
• to globally substitute g/word/s//newword/g
  
• regex expressions, examples:
  whole words \<word\>
  empty lines ^$
  letters and numbers [0-9a-z]
  not [^a-zA-Z0-9 ]
  
• changing to Vi mode but does things Vi cannot do
  
• Write
  
• Quit
  

Very few/no customizations required
Execute a shell command, or filter lines through a shell commands:
[range]! argument(s)
Add a comment: "
Join lines: :[range] j
Previous file: :prev
Next file: :n
Read the contents of another file after line in current file: 1r [filename]
Show current version of ex: :ve
Write a range of lines to another file – 1,4 w >> [filename]
Go from ex to vi :vi
Go from vi to ex: Q
Shift lines: >> <<
Show the last line: =
Change directory: chdir/cd
Edit a different file: :e
Help for any ex command: :exu[sage]
Display and optionally change the file name: f [newname]
Append after line X: :a
Insert before line X: :i
Create mark: :ma[x]
Goto mark '[x]
Make an excrc file: :mkexrc (This writes abbrevs, editor options
and maps to specific file)
Create abbreviations: :ab teh the
Preserve current state of the file and later recover with ex -r::pre

• To remove double spaces: g/ *// /g
  

It was based on a program called EM,
which in turn was an improvement of ED
one of the original authors of Unix.
Ex is a simple but useful tEXt editor
which is not to be confused with VIM.
also by Bill Joy.
VIM was only a much later development,
But back to EX which is the focus of this video.
EX is a very simple editor helpful for
configuring system files.
Ex is provided by default on Windows, Linux and BSD.
It is the default editor in OpenBSD.
This is how it works.

• starting up EX
  
• Ex does some amazing things
  
• set line numbers - .exrc
  
• to copy(co), move(m), change(c)
  
• undo a change (u)
  
• to append text: a
  
• to save and quit: w q
  
• find a word /word g/word
  
• to substitute s/word/ newword/g
  

whole words \<word\>
empty lines ^$
letters and numbers [0-9a-z]
not [^a-zA-Z0-9 ]
Replace spaces at the beg. of a line: g/^ */s///
Typing vi at the prompt changes to Vi Mode.
But there are some things Ex does better than Vi.

• Write
  

Replace trailing whitespace: g/ *$///
Delete all blank lines: g/^$/d (d = delete)
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