[SunRescue] Re: [SunRescue]Tiny executables

[Ken Hansen]

In the Mainframe operating systems, starting with OS/360 back in th
emid-sixties, they had utility called IEFBR14.

IEFBR14 was, simply, a Branch and Return, Register 14 instruction (aprox. 4
bytes wide, IIRC the IBM 360 was 32-36 bit processor). Again, it's purpose
was to provide an execution "stub" to give the OS a cahnce to do some file
maint.

Later, the program *ballooned* to two instructions - an instruction was
added to set the return register to zero, *then* Branch and Return, based on
the value in register 14.

It is/was an extremely powerful utility for a mainframe JCL coder.

Ken

----- Original Message -----
From: "Paul Sladen" <paul at sladen.org>
To: <rescue at sunhelp.org>
Sent: Thursday, May 17, 2001 7:19 AM
Subject: Re: [SunRescue] SS5 upgrade


> On Wed, 16 May 2001, Dave Reader wrote:
>
> > As an interesting (or maybe not) deviation from the topic, a silly
thread
> > came up on another list i take today.. about the size of /bin/true (and
> > how it really is bloated for something that does nothing). It was noted
> > that SunOS and Solaris /bin/true is a shell script which just exits, and
> > hence fires up a shell to do it. My linux boxen use a binary, so I
looked
> > at how it varies by platform...
>
> The Page to check out here is:
>
>   http://www.muppetlabs.com/~breadbox/software/tiny/teensy.html
>
> How to build a 45 byte ELF binary executable /bin/true.
>
> Have Fun,
> Paul
>
> (hint; what happens if you put the executable code *inside* the ELF header
;-)
>
> --
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>
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