On 3/29/15 5:03 AM, isabella parakiss wrote:
> $ read -n 100 a b <<< 'x y'; declare -p a b
> declare -- a="x"
> declare -- b="y"
> $ read -N 100 a b <<< 'x y'; declare -p a b
> declare -- a="x y
> "
> declare -- b=""
>
> From my understanding of the documentation, read -N should ignore the
> delimiter (-d), not the IFS. If the current behaviour is correct, a
> better wording may be helpful.
Yes, it appears that the current wording leads to invalid assumptions
about the behavior of -N. The feature is implemented as Richard Stallman
originally requested it:
"We want to make a shell script reliably read the first few characters
from standard input and save them in a variable...I suggest an option for
`read' that says to read exactly a certain number of characters. Perhaps
`read -c NUMBER'."
There was some back-and-forth back in late 2009 about features and
syntax and the current implementation is the result. I proposed a
combination of -n, -d DELIM, and $REPLY, but rms's request was for a
more general mechanism. (-N does not imply -r, though maybe, in
hindsight, it should have.)
The text reading "read exactly N characters" was intended to imply this,
but I can make it more explicit.
Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU [email protected] http://cnswww.cns.cwru.edu/~chet/
