Subject: Re: discrepency beteen /bin/echo and builtin echo of /bin/sh
From: David Laight <email@example.com>
Date: 06/13/2002 13:55:02
> You seem to be completely missing the point. I'll try to explain more
> slowly, and not to assume that you've read all of the standard.
> With POSIX and SUS, the terms "option", "operand", and "argument" have
> specialised meanings. An argument is one of the strings passed as part of
> argv to a utility. Some of these arguments contain options, some of them
> contain option-arguments, at most one of them contains the end-of-options
> delimeter, and the rest are operands. Note that this means that no argument
> can both contain options and be an operand. See
> <http://www.opengroup.org/onlinepubs/007904975/basedefs/xbd_chap12.html> for
> more details.
ok, I was probably being loose with these terms....
> Now, the specification for "echo" explicitly states that it shall not
> recognise "--" as the end-of-options delimiter, but as an operand.
> Thus, in the command-line "echo -- foo", there are two operands, "--" and
Is there any sensible rational for this?
(apart from historical precedent and paranoia)
> The interesting question is how we analyse the command-lines "echo -n foo"
> and "echo -e foo". Specifically, are "-n" and "-e" options or operands?
> How about in "echo -e -n foo" and "echo -n -e foo"?
or "echo -en foo" or "echo -n -n foo"
(netbsd's ksh builtin echo is particularly broken here...)
I suspect it would actually be best to 'bite the bullet' and make
echo getopts(3) conformant supporting options n, e and E.
(where an implementation may default to -E or -e).
Unfortunately the SuS (and posix?) explicitely forbid this :-(
The reason I had 3 behaviours was that the (online) SuS disallowed
all options (or first arguments of -n), and I thought that the posix
spec disallowed options other than -n.
This meant (I thought) that the current netbsd (sh builtin) echo was neither
a XSI (SuS) echo, nor posix compliant.
Some versions of echo:
netbsd /bin/echo -n
netbsd sh -n or -e
netbsd csh -n
netbsd ksh [-neE]
solaris8 (all) expands \x
UW2 /bin/echo -n, expands \x
UW2 sh -n, expands \x unless /usr/ucb before /usr/bin
UW2(ATT) ksh not sure - I've only got the source, and I'm
not sure what gets compiled, could do many things!
could easily depend on whether $PATH hits
/bin/echo before anything else....
David Laight: firstname.lastname@example.org