Re: dash: read does not ignore trailing spaces

[Stephane Chazelas <stephane.chazelas@gmail.com>]

2015-12-03 22:02:14 +0100, Harald van Dijk:
[....]
>   $ for shell in bash mksh posh zsh; do printf %s: "$shell"; $shell
> -c 'IFS=,; echo a, | { read v; echo "<$v>"; }'; done
>   bash:<a>
>   mksh:<a>
>   posh:<a,>
>   zsh:<a,>
> 
> As far as I can tell, the posh/zsh behaviour is the correct
> behaviour, but I'm not convinced yet my interpretation is correct.
[...]

No, that would be the same as for:

v=a:b:
IFS=:
set -f

set -- $v

It's meant to split into "a" and "b", not "a", "b" and "". As
":" is meant to be treated as a *delimiter* or *terminator*.

That has been discussed a few times on the austin group mailing
list.

zsh and pdksh (and other descendants of the Forsyth shell) treat it as
separator (and are not compliant), mksh (derived from pdksh)
changed it recently. posh (also based on pdksh) still hasn't changed it.

That's a bit counter-intuitive and means for instance you can't
use $IFS to split variables like $PATH/$LD_LIBRARY_PATH...

In the case of read, it even makes less sense because:

~$ echo a:: | sh -c 'IFS=: read a; echo "$a"'
a::
~$ echo a: | sh -c 'IFS=: read a; echo "$a"'
a

But that's how it's specified.

So dash is indeed conformant there.

-- 
Stephane