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From: bayes@hpislx.HP.COM (Scott Bayes)
Newsgroups: comp.sys.mac.programmer
Subject: Re: mac sh wanted
Message-ID: <9710008@hpislx.HP.COM>
Date: 13 Nov 90 19:53:27 GMT
References: <1990Nov10.163234.20256@cunixf.cc.columbia.edu>
Organization: Measurement Systems Operation - Loveland, CO
Lines: 109

> BTW: What IS the format of shell archives anyways?
> ______________________________________________________________________________
> Donald Burr, c60a-cz@danube.Berkeley.edu  | "I have a seperate mail-address
> University of California, Berkeley        | for flames and other such nega-
> Majoring in Computer Science              | tive msgs; it's called /dev/null."

All the shell archives I've seen tend to be a procedural format.  That
is, the files to be archived tend to be copied as or converted to text,
and packaged together with shell commands that, when executed by a
shell, unpack them, put them in the right places, set their UN*X
permissions, etc.  Binary files tend to be converted to ASCII, and an
"unpacker" program source and compilation instructions included with
them (i.e.  to unpack a shar [shell archive] file that contains a
binary, you'll probably need a C compiler on-line).

It's hard to imagine being able to un-shar a shar file without a decent
emulation of a UN*X shell doing the job.

Below is an example sharfile containing a binary file and a text file,
both very short.  The binary unpacks to contain an escape char followed
by "Hello", and the text file contains "hello world".  It works on an
HP300 HP-UX machine Revision 7.0 or 7.03, under Bourne Shell (sh).  I
have seen slightly variant formats used.

I created the shar with:

$ shar testshar testshar2 > test.shar


Scott Bayes
-----------------------------------------------------------------------------
# This is a shell archive.  Remove anything before this line,
# then unpack it by saving it in a file and typing "sh file".
#
# Wrapped by Scott Bayes <bayes@hpislsfb> on Tue Nov 13 12:46:56 1990
#
# This archive contains:
#	testshar	testshar2	
#

LANG=""; export LANG
PATH=/bin:/usr/bin:$PATH; export PATH


rm -f /tmp/uud$$
(echo "begin 777 /tmp/uud$$\n \nend" | uudecode) >/dev/null 2>&1
if [ -f /tmp/uud$$ ]
then
	rm -f /tmp/uud$$
	unpacker=uudecode
else
	echo Compiling unpacker for non-ascii files
	pwd=`pwd`; cd /tmp
	cat >unpack$$.c <<-'EOF'
	#include <stdio.h>
	#define DEC(c)	(((c) - ' ') & 077)
	main()
	{
		int n;
		char dest[128], a,b,c,d;

		scanf("begin %o ", &n);
		gets(dest);

		if (freopen(dest, "w", stdout) == NULL) {
			perror(dest);
			exit(1);
		}

		while ((n=getchar()) != EOF && (n=DEC(n))!=0)  {
			while (n>0) {
				a = DEC(getchar());
				b = DEC(getchar());
				c = DEC(getchar());
				d = DEC(getchar());
				if (n-- > 0) putchar(a << 2 | b >> 4);
				if (n-- > 0) putchar(b << 4 | c >> 2);
				if (n-- > 0) putchar(c << 6 | d);
			}
			n=getchar();
		}
		exit(0);
	}
	EOF
	cc -o unpack$$ unpack$$.c
	rm unpack$$.c
	cd $pwd
	unpacker=/tmp/unpack$$
fi

echo x - testshar '[non-ascii]'
$unpacker <<'@eof'
begin 666 testshar
'&TAE;&QO"AX 
 
end
@eof

chmod 666 testshar

echo x - testshar2
cat >testshar2 <<'@EOF'
hello world
@EOF

chmod 666 testshar2

rm -f /tmp/unpack$$
exit 0