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From: Pietro Gagliardi <pietro10@mac.com>
Date: Wed, 26 Mar 2008 14:58:26 -0400
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] bug in echo?
Topicbox-Message-UUID: 827f9776-ead3-11e9-9d60-3106f5b1d025

Is there a valid reason to have echo process the arguments given?
It's a simple mod:

	#include <u.h>
	#include <libc.h>

	/* echo:  echo args */
	void
	main(int argc, char *argv[])
	{
		int nl = 1;

		ARGBEGIN{
		'n':
			nl = 0;
			break;
		default:
			fprint(2, "usage: echo [-n] stuff\n");
			sysfatal("usage");
		}ARGEND;
		for(i = 1; i < argc - 1; i++)
			print("%s ", argv[i]);
		print("%s%s", argv[argc - 1], nl ? "\n" : "");
		exits(0);
	}

However, Plan 9 has gone for years and people have not had this
problem. (Then again, so did TUPE for Unix).

Can we stick with

	echo -n '-n
	'

as Rob (the coauthor of that book, mind you, so he knows EXACTLY what
he is saying) said? It defies the need for handing a single argument.

If we start supporting arguments, we can have other arguments:

	-e		Use escape sequences.
	-E		Use no escape sequences.
	-l (ell)	One per line.
	-t		Separate with tabs.
	-Nn		Use n spaces (default 1).
	-L		If -l is given, use line numbers.
	-o		Output each character in octal.
	-x		Output each character in hex.
	-v		Make non-printing characters visible.
	-r		The first argument is a regular expression. Print each string
given as an argument that matches this regular expression.

and no doubt people will want them. Is this necessary? echo -e is
considered harmful (and when I started /bin/sh programming, I didn't
like that it wasn't default. Oh well).

The lesson?
	echo -n '-n
	'
is the solution.