Path: utzoo!mnetor!uunet!husc6!bloom-beacon!tut.cis.ohio-state.edu!mailrus!nrl-cmf!cmcl2!beta!unm-la!unmvax!sandia!marms
From: marms@sandia.UUCP (Mike Arms)
Newsgroups: comp.binaries.ibm.pc
Subject: Re: Thanks, I'd rather do it myself
Message-ID: <254@sandia.UUCP>
Date: 8 Apr 88 00:30:33 GMT
References: <2237@ttidca.TTI.COM>
Reply-To: marms@sandia.UUCP (Mike Arms)
Organization: The Dark Gnat Returns
Lines: 23
Keywords: self extracting arc
Summary: could use "dd", but slow

In article <2237@ttidca.TTI.COM> clark@ttidca.TTI.COM (Ralph Clark) writes:
>Here is a simple program to convert a self-extracting archive back into
>a regular you-can-run-arc--t-on-it-before-you-spend-an-hour-downloading-it
>archive. Inquiry to three local gurus failed to produce a simple one-line
>shell command alternative. It will undoubtedly fail if you ask it to delete
>a googolplex of bytes from the head of a file.


There is indeed a fairly simple one-line Unix command to do exactly this
using "dd", but it is VERY slow compared to your C-program. You must
specify the block size and the skip option to "dd":

      dd bs=1 skip=9758 <sky.exe >sky.arc

On my Sun 3/60, I ran a time comparison just for grins. The "dd" took
4.5 minutes, while "lobotomy" only took 1 second. They produced exactly
the same output. Most likely "dd" would move a hell of a lot faster if
it wasn't bogged down with a 1 byte block size specifier. Thanks for
a simple, but useful solution to the self-extracting arcs problem.

-- 
Mike Arms
uucp:  ...{ucbvax | gatech}!unmvax!sandia!marms