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From: mjp@spice.cs.cmu.edu (Michael Portuesi)
Newsgroups: comp.sys.amiga
Subject: AmigaDOS script hacking: flames
Message-ID: <1249@spice.cs.cmu.edu>
Date: Thu, 30-Jul-87 18:20:23 EDT
Article-I.D.: spice.1249
Posted: Thu Jul 30 18:20:23 1987
Date-Received: Sat, 1-Aug-87 11:04:02 EDT
Reply-To: mjp@spice.cs.cmu.edu (Michael Portuesi)
Organization: Carnegie-Mellon University, CS/RI
Lines: 54

Keywords:


I decided to experiment with AmigaDOS script-hacking, just to see how
far I could push it.  Often, I download software from Usenet or other
places in big batches and place it in subdirectories on a disk.  It
would be nice if I could run a command from the root directory on
every file that matched a pattern anywhere on disk, much like the ALL
keyword for COPY and DELETE.  This way, I could un-shar every .sh file
on a disk with just one command, e.g.

	EXECUTE apply "shar -u $name" #?.sh

Armed with the AmigaDOS manual, I began my task.  Realizing that
AmigaDOS does not allow iteration over the results of a command, like
the "foreach" statement in csh, I opted to direct the output of DIR to
a file and run it through EDIT to create a file of executable commands
that I would EXECUTE.

DIR, while offering an option to do a recursive directory list, also
outputs its information in a two-column format that is impossible to
parse with EDIT.  LIST, while offering a listing that is easily
interpreted by other programs, does not offer a recursive directory
search.  Grrr.

So I decided to use DIR to list just the subdirectories of the current
directory to a file.  Then I would run that through EDIT to create a
batch of LIST commands that would generate all the file names, plus
instructions to concatenate those into one big file.  This file would
be run through EDIT once again to create the executable commands, and
then executed.  It is easy to run EDIT in batch mode.  It is easy to
use ECHO to create a command file for EDIT.  But when the necessary
commands for EDIT exceed one line, you're hosed because ECHO can only
handle one line of input, and AmigaDOS doesn't know how to redirect
output by appending to the end of a file!

So what have I learned from this?

	1) The CLI and the EXECUTE command are unsuitable for
	   general-purpose shell hacking.

	2) The AmigaDOS commands weren't written with batch processing
	   of any type in mind.

	3) Not only is EDIT a lose as an interactive line editor, it
	   is also a very bad stream editor.

	4) I'll try this again with Matt's Shell at the earliest
	   opportunity.
-- 

Mike Portuesi / Carnegie-Mellon University Computer Science Department
ARPA:	mjp@spice.cs.cmu.edu	UUCP: {backbone-site}!spice.cs.cmu.edu!mjp
BITNET:	rainwalker@drycas (a uVax-1 run by CMU Computer Club...tons o' fun)

"Paradise is exactly like where you are right now...only much, much better"
			--Laurie Anderson, "Lanugage is a Virus"