[BusyBox] Sed and vi.

Rob Landley rob at landley.net
Sat Oct 11 21:42:09 UTC 2003

On Saturday 11 October 2003 11:45, Wolfgang Denk wrote:
> In message <200310110119.01208.rob at landley.net> you wrote:
> > > > I think they might be ed commands, which is about the same as sed.
> > >
> > > You gess wrong. ed is not even nearly the same as sed.
> >
> > Today, no.  Thirty years ago, they were almost exactly the same, having
> > derived from the same code base.  (Filter out the gnu extensions and
> > they're a lot closer.)
> You are wrong again, and on both accounts: the commands are not  even
> nearly  the  same,  and  the sources are very different. Feel free to
> check for example with the Unix Seventh Edition Manual at
> http://www.cs.bell-labs.com/7thEdMan/

Actually I was going by an old interview with Ken Thompson.  I don't really 
read troff.  (I've helped debug doclifter to obsolete troff, but it was 
mostly finding bugs and producing test cases).

However, http://www.cs.bell-labs.com/7thEdMan/vol2/sed says the purpose of sed 

> To edit any size file when the sequence
> of editing commands is too complicated to be comfortably
> typed in interactive mode.
> The principal loss of functions compared to an interactive editor
> are lack of relative addressing (because of the line-at-a-time
> operation), and lack of immediate verification that a command has
> done what was intended.
> Sed is a lineal descendant of the UNIX editor, ed.  Because of the
> differences between interactive and non-interactive operation,
> considerable changes have been made between ed and sed;
> even confirmed users of ed will frequently be surprised (and probably
> chagrined), if they rashly use sed without reading Sections 2 and 3 of this
> document.

That paragraph may be what you're talking about, but it doesn't exactly imply 
that it's useless to go looking for shared code, either.

On the other hand, I can't say I've ever actually USED ed.  Bill Joy wrote vi 
when I was 4 years old.  (I did use edlin under dos.  This is why I've never 
tried ed.)

> Best regards,
> Wolfgang Denk
> [who used to run Unix 7th ed. on a PDP11 some decades ago]

Unix V7 came out in January, 1979.  (I was just about to turn seven.)  I've 
studied it, but you've got me out-fogeyed here. :)


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