From: Wybo Dekker <wybo@...>
Date: 2005-01-31T22:47:49+09:00
Subject: Re: perl's -t and -B file tests in ruby?

On Mon, 31 Jan 2005, Tim Heaney wrote:

> ts <decoux@moulon.inra.fr> writes:
> >
> > W> -B : file is binary
> >
> >  Define what is a binary file ?
> 
> In this context, Perl essentially means that the file has a lot of
> non-ASCII characters. From the perlfunc man page
> 
>     -T  File is an ASCII text file (heuristic guess).
>     -B  File is a "binary" file (opposite of -T).
> 
> and 
> 
>     The "-T" and "-B" switches work as follows.  The
>     first block or so of the file is examined for odd
>     characters such as strange control codes or char-
>     acters with the high bit set.  If too many strange

In Larry Wall's Reference    here ^   he adds:
      (that don't look like UTF-8)

>     characters (>30%) are found, it's a "-B" file,
>     otherwise it's a "-T" file.  Also, any file con-
>     taining null in the first block is considered a
>     binary file.  If "-T" or "-B" is used on a file-
>     handle, the current IO buffer is examined rather
>     than the first block.  Both "-T" and "-B" return
>     true on a null file, or a file at EOF when testing
>     a filehandle.  Because you have to read a file to
>     do the "-T" test, on most occasions you want to
>     use a "-f" against the file first, as in "next
>     unless -f $file && -T $file".
> 

-- 
Wybo