sharchive

sharchive
 /shar'ki:v/, n.

   [Unix and Usenet; from /bin/sh archive] A {flatten}ed representation
   of a set of one or more files, with the unique property that it can be
   unflattened (the original files restored) by feeding it through a
   standard Unix shell; thus, a sharchive can be distributed to anyone
   running Unix, and no special unpacking software is required.
   Sharchives are also intriguing in that they are typically created by
   shell scripts; the script that produces sharchives is thus a script
   which produces self-unpacking scripts, which may themselves contain
   scripts. Sharchives are also commonly referred to as `shar files'
   after the name of the most common program for generating them.

   The downsides of sharchives are that they are an ideal venue for
   {Trojan horse} attacks and that, for recipients not running Unix, no
   simple un-sharchiving program is possible; sharchives can and do make
   use of arbitrarily-powerful shell features. For these reasons, this
   technique has largely fallen out of use since the mid-1990s.
    

shar
sharchive
shar file

   <tool, file format> ("Shell archive", after {ar} and {tar})
   Any of the many {Unix} programs that creates a {flatten}ed
   representation of one or more files, with the unique property
   that it can be unflattened (the original files extracted)
   merely by feeding it through a standard {Unix} {shell}.  The
   output of shar, known as a "shar file" or "sharchive", can be
   distributed to anyone running {Unix}, and no special unpacking
   software is required.

   Sharchives are intriguing in that they are typically created
   by shell scripts; the script that produces sharchives is thus
   a script which produces self-unpacking scripts, which may
   themselves contain scripts.  The disadvantage of sharchives
   are that they are an ideal venue for {Trojan horse} attacks
   and that, for recipients not running Unix, no simple
   un-sharchiving program is possible; sharchives can and do make
   use of arbitrarily-powerful shell features and other Unix
   commands.

   Different implementations of shar vary in sophistication.
   Some just {uuencode} each input file and output commands to
   {uudecode} the result, others include extensive checking to
   make sure the files have been transferred without corruption
   and that all parts of a multi-file sharchive have been
   unpacked.

   The {unshar} utility strips off mail and news headers before
   passing the remainder of its input to sh.

   (1996-10-18)