Stephane Chazelas <stephane.chaze...@gmail.com> wrote:
> One more major issue identified in this thread is that in TC2,
> the "until" in
>
> < file until...
>
> or:
>
> foo=bar until...
>
> is now required to be recognised as the "until" keyword, and
> it's not in most shells (an exception is zsh for the first
> case).
Could you explain since when this is required?
>From what I can tell, a macro assignement before one of the complex commands
"if", "case", "while", ... never works.
It is however a bug that the Bourne Shell and it's derivates like ksh and bosh
do not allow a I/O redirection before such a command since it is permitted
after a command already.
> < file time cmd
> < file ! cmd
> a=1 ! cmd # that one unclear whether the a=1 would apply to all
> # the commands in the pipeline though
> < file { ...; }
>
> as an extension.
< file time cmd already works in Bourne Shell and it's children
< file ! cmd The fact that this does not work must be seen
as a bug since both constructs are parsed the same way.
> BTW, several shells (ksh93, mksh, zsh) support: < file (subshell)
> I've not checked whether that was allowed/required/prohibited by
> the POSIX grammar.
>
> See also:
>
> $ ksh -c '< file f() { echo x; }; typeset -f'
> f() { echo x; }; # missing newline
This seems to be a funny bug as it looks like ';' is written instead of a
newline ;-)
> $ zsh -c '< file f() { echo x; }; typeset -f'
> f () {
> echo x
> } < file
This looks like a bug: the command that is redirected is the function
definition, so "< file" does not belong here.
BTW:
bosh -c '< file f() { echo x; }; type -F'
f(){
echo x
}
Note that "typeset" is not part of POSIX, bosh therefore uses "type -F" as
discussed on the POSIX teleconferences and bug reports.
mksh -c '< file f() { echo x; }; typeset -f'
mksh: syntax error: '(' unexpected
Nice Bug.
> $ ksh -c 'f() < file (echo x); typeset -f'
> ksh: syntax error at line 1: `<' unexpected
This is illegal syntax, a corrected variant of what you seem to intend is e.g.:
bosh -c 'f() { < file (echo x); }; type -F'
f(){
(echo x) 0<file
}
BTW: ksh works here as well.
Note that the syntax-tree -> text converter in bosh is highly tested as it is
used while parsing $(cmd) constructs and $(cmd) would not work if the result
from the syntax-tree -> text converter did create text that is not accepted by
the parser to create the same syntax tree again.
> $ mksh -c 'f() < file (echo x); typeset -f'
> f() ( echo x ) <file
> $ zsh -c 'f() < file (echo x); typeset -f'
> f () {
> (
> echo x
> ) < file
> }
As mentioned: if this works, the related shell has a parser bug.
Jörg
--
EMail:jo...@schily.net (home) Jörg Schilling D-13353 Berlin
joerg.schill...@fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/
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