Re: [PATCH] man: document what happens when IFS= (and when it's not)

On Sat, Apr 22, 2023 at 05:16:21PM +0200, наб wrote:
> A question I just got from a user was "how do I make while read -r l; do
> ...; done < f not strip the initial tabs?". Turns out, the manual is
> silent on this, and POSIX just about implies this behaviour.
> (Indeed, our read is almost verbatim POSIX, and both defer to Field
>  Splitting, but our Field Splitting isn't nearly as detailed,
>  and thank god.)
> Even POSIX spends just one line describing this pivotal behaviour
> (Issue 8 Draft 2.1 line 75044-75045:
> "2. If the value of IFS is null, field splitting shall have no effect,
>     except that if the input is empty the result shall be zero fields.),"
> and when I first encountered this it was also quite surprising to me.
> 
> Spell it out explicitly: IFS= means that input is preserved,
> and the default value means whitespace is stripped from the front.
> Drive it home with an example because it's esoteric (and I know from
>  that user that they first tried searching for read in the manual,
>  but it was not very helpful).
> 
> Reported-by: rozbrajaczpoziomow <[email protected]>
> ---
>  src/dash.1 | 13 +++++++++++++
>  1 file changed, 13 insertions(+)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt