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Re: sh compatibility again :->
- X-seq: zsh-workers 1941
- From: "Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxxxxxxxxx>
- To: Zoltan Hidvegi <hzoli@xxxxxxxxxx>, borsenkow.msk@xxxxxx, zsh-workers@xxxxxxxxxxxxxxx
- Subject: Re: sh compatibility again :->
- Date: Sun, 11 Aug 1996 21:36:34 -0700
- In-reply-to: Zoltan Hidvegi <hzoli@xxxxxxxxxx> "Re: sh compatibility again :->" (Aug 12, 4:18am)
- References: <199608120218.EAA03734@xxxxxxxxxxxxxxxxxxxx>
- Reply-to: schaefer@xxxxxxx
On Aug 12, 4:18am, Zoltan Hidvegi wrote:
} Subject: Re: sh compatibility again :->
}
} Andrej Borsenkow wrote:
} [...]
} > 1. It doesn't like malformed constructs like
} >
} > A="`cat /some/file" (note missed backtick)
} >
} > zsh tries to parse command substitution behind closing double-quote, and
} > ends up with `missing "' at the end of script. Our /bin/sh stops at
} > closing double-quote. In POSIX the result is undefined - thus, techically
} > neither violate it.
}
} I copied the behaviour of bash here. pdksh also behaves this way.
Right; if I recall correctly, bash and ksh both permit stuff like:
$ echo "foo `echo "bar baz"` boing"
That is, bash and ksh nest double quotes inside backticks. Old-fashioned
Bourne shell, on the other hand, does NOT permit nesting of double quotes,
even inside backticks. So in bash/ksh the above is parsed as
(echo) (foo `echo "bar baz"` boing)
but in sh it is
(echo) (foo `echo bar) (baz` boing)
The only way to resolve this would be with yet another option, SH_QUOTES
or some such. Worth it? Dunno.
} > But the following things could probably be fixed
} >
} > 4. Traditional /bin/sh interprets `set -' as set +xv.
}
} OK. I've changed that. set - will be the same as set +xv and
} set - args will be the same as set +xv -- args.
Hmm. So what's the approved way of setting $1 to "-x"? `set -- -x`?
And is `set --` equivalent to `shift $#`, since `set -` is not?
Are you sure `set - args` should act like `set +xv -- args`?
I can't say I'm entirely excited about this change.
} > 5. Currently zsh sets BSD_ECHO when running as sh. Our sh does support
} > escapes in echo; I recall that SCO sh does it as well. I don't know about
} > others. What about relaxing it? If scripts doesn't rely upon escapes in
} > echo, it would make no harm.
}
} I'll try to write a configure check for the echo style of /bin/sh and use
} that.
Eww, no. Let's pick one behavior and stick with it, please. The default
options, even in an emulation mode, shouldn't vary from one installation
to the next! It's been a long time since I encountered an sh that didn't
have a builtin SysV-style echo -- BSD_ECHO is needed mostly for csh
compatibility. I'd vote for leaving BSD_ECHO off when run as "sh".
--
Bart Schaefer Brass Lantern Enterprises
http://www.well.com/user/barts http://www.nbn.com/people/lantern
New male in /home/schaefer:
>N 2 Justin William Schaefer Sat May 11 03:43 53/4040 "Happy Birthday"
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