"a.out"

[Bill Hogan <bhogan@rahul.net>]

"KMH" == Karl M Hegbloom <karlheg@bittersweet.or.us> writes:

  >>>>>> "Bill" == Bill Hogan <bhogan@rahul.net> writes:

  Bill> According to "The Magic Garden Explained" [GoodHeart and
  Bill> Cox, Prentice-Hall, 1994] the terms "Extensible Library
  Bill> Format" (ELF) and "Common Object Format" ("COFF") are
  Bill> different ways of _organizing_ the information in a.out
  Bill> files.

  Bill> pre-SVR4 => COFF (ELF did not exist?)

  Bill> SVR4+ => ELF is default but COFF still supported

  Bill> I still have the impression that "executable binary" is
  Bill> an acceptable substitute for "a.out" when the context is
  Bill> clear.
	
  KMH> I noticed that when I compiled an example program without giving the
  KMH> '-o' option to the compiler, it generated a file called a.out, and
  KMH> when I did 'chmod +x a.out ; a.out' the program ran.  I didn't try the
  KMH> 'file' command on it to divine its magic...  I should try that and
  KMH> see; -- bet it's ELF because gcc 2.7.2 generates ELF by default.

  KMH> What's QMAGIC mean?

   I don't know. It's listed more than once in /etc/magic.

  KMH> There must be a historical reason for the name a.out. 

   The earliest reference I have found to the term `a.out' is
Kernighan's & Ritchie's "The C Programming Language [Prentice-Hall,
1978], which gives it two index entries:

	[p.6] "... compilation will .. make an executable file called
_a.out_. Running that [file] by [issuing] the command

	a.out

[will execute the program]"

	[p.68] "... the command

	cc main.c getline.c index.c

compiles the three files, places the resulting relocatable object code
in files main.o, getline.o, and index.o, and loads them all into an
executable file called _a.out_."

    Goodheart and Cox give two published references relating to COFF &
ELF formats.

    * Gircys, "Understanding and Using COFF", O'Reilly, 1988

    * Nohr, "Unix SVR4 Understanding and Using ELF", Prentice-Hall,
1993.

  KMH> I will look into that book.  Do you happen to have a bibliography
  KMH> handy?  

    No, just heard it on the grapevine. ISBN 013-098138-9

    I don't get to the library as often as I should.

    Cheers,
     Bill

-- 
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