Re: [PATCH] split: --chunks option

[Pádraig Brady]

On 15/12/09 22:46, Chen Guo wrote:
> Hey guys,
>      Alright as of now everything that we originally talked about has been
> implemented; tests were done on an 980K ASCII file while limiting buffer
> size to 2 bytes (will test on binary later). Everything works great

great stuff.

> As of now, I've got the following syntax:
>      -bN or --bytes=N is original usage
>      -b/N or --bytes=/N is split into N equal sized files
>      -bK/N or --bytes=K/N is extract Kth of N equal chunks to stdout
> -nN is equivalent to -b/N, and -nK/N is equivalent to -bK/N
>
> > Right. Also doing -n lines:4 would allow one to specify
> > a distribution method which may be required. I.E. this
> > could be used to specify round robin distribution of lines
> > which might be required.
> >
> > -n lines-rr:4
> I haven't handled the non-seekable file case yet, but yeah this works.
> As for extracting byte-chunks to stdout, I see no other way than to
> read from the file's start and start outputting when the desired chunk
> is read.
>
> > Also specifying other delimiters might be useful like:
> >
> > -n nul:4
>
> Actually at the top of split.c I see a TODO that talks about a -t option
> which specifies a CHAR or REGEX deliminator. REGEX might be
> kind of complicated, but a delim char as a global char eol should
> be trivial to implement. We can leave eol = '\n' by default, and the -t
> option can override it.

Right, -t is probably more general as it would also support
the existing --lines option.

> But then this begs the question... How would you enter say, '\0' into
> the terminal? And the way I know of entering newline is rather awkward:
> -t '
> '

I'd probably use escapes like the join command does.
For example, it supports: -t '\0'

For reference bash and ksh support ansi c quoting like $'\0'
so you could specify -t $'\0'. Also more generally one could do:
-t $(printf '\0'), though I wouldn't depend on those being available,
and also passing NULs at least through the command line will be problematic.

> And last thing, would I be wrong to say we can't support splitting by
> chunks with stdin? Barring of course, the round robin line splitting.

Right, that's all I can see possible for non seekable files.

cheers,
Pádraig.