Command:   ed - editor
Syntax:    ed file
Flags:     (none)
Example:   ed prog.c                # Edit prog.c

     Ed is functionally equivalent to the standard  V7  editor,  ed.  It
supports the following commands:

      (.)  a: append
      (.,.) c: change
      (.,.) d: delete
           e: edit new file"
           f: print name of edited file"
      (1,$) g: global command
      (.)  i: insert
      (.,.+1) j: join lines together
      (.)  k: mark
      (.)  l: print with special characters in octal
      (.,.) m: move
      (.,.) p: print
           q: quit editor"
      (.)  r: read in new file
      (.,.) s: substitute
      (1,$) v: like g, except select lines that do not match
      (1,$) w: write out edited file

Many of the commands can take one or two addresses, as indicated  above.
The  defaults  are  shown in parentheses.  Thus a appends to the current
line, and g works on the whole file as default. The dot  refers  to  the
current  line.   Below  is  a sample editing session with comments given
following the # symbol.

      ed prog.c               # Edit prog.c
      3,20p                   # Print lines 3 through 20
      /whole/                 # Find next occurence of whole
      s/whole/while/          # Replace whole by while
      g/Buf/s//BUF/g          # Replace Buf by BUF everywhere
      w                       # Write the file back
      q                       # Exit the editor
Ed is provided for its sentimental value.  If you want  a  line-oriented
editor, try ex.  If you want a good editor, use elle, elvis, or mined.