Bug#498336: grep: option to filter non-printable characters from contents

[Santiago R.R.]

Dear grep upstream authors,

I'd like to forward this bug reported to debian
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=498336

On Tue, 9 Sep 2008 11:07:33 +0200 Vincent Lefevre  wrote:
…
> 
> grep should have an option to filter non-printable characters from
> the contents (file contents, but also filenames -- see bug #42630)
> *before coloring*. The values could be "never", "always" and "auto",
> like with --color.
> 
> Such an option would be useful because:
> 
> 1. The option --binary-files is a heuristic only; the user may want
>to have more information on binary files anyway.
> 
> 2. It is not even possible to write a wrapper script when coloring is
>used, because after coloring, it is not possible (or at least very
>difficult) to do the difference between escape sequences from grep
>and those from the original contents.
> 
> Such non-printable characters could be either replaced by some
> locale-specific replacement character or transcoded.
> 
> I wonder whether filtering should be the default when the output
> is connected to a terminal (and when POSIXLY_CORRECT is not set).
> It would not be worse than the default --binary-files=binary.
…

This option could be also useful to filter undesirable behaviors, such
as ringing the bell terminal (from stdin in this case):

printf '\a'x | grep x

What's your position on this?

Thanks,

  -- Santiago

PS. As Vincent Lefevre says, this bug relates to filtering non-printable
characters from filenames:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=42630

Bug#498336: grep: option to filter non-printable characters from contents

[Vincent Lefevre]

Package: grep
Version: 2.5.3~dfsg-6
Severity: wishlist

grep should have an option to filter non-printable characters from
the contents (file contents, but also filenames -- see bug #42630)
*before coloring*. The values could be never, always and auto,
like with --color.

Such an option would be useful because:

1. The option --binary-files is a heuristic only; the user may want
   to have more information on binary files anyway.

2. It is not even possible to write a wrapper script when coloring is
   used, because after coloring, it is not possible (or at least very
   difficult) to do the difference between escape sequences from grep
   and those from the original contents.

Such non-printable characters could be either replaced by some
locale-specific replacement character or transcoded.

I wonder whether filtering should be the default when the output
is connected to a terminal (and when POSIXLY_CORRECT is not set).
It would not be worse than the default --binary-files=binary.

-- System Information:
Debian Release: lenny/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.26.3-20080822 (SMP w/2 CPU cores; PREEMPT)
Locale: LANG=POSIX, LC_CTYPE=en_US.ISO8859-1 (charmap=ISO-8859-1)
Shell: /bin/sh linked to /bin/bash

Versions of packages grep depends on:
ii  libc6 2.7-13 GNU C Library: Shared libraries

grep recommends no packages.

grep suggests no packages.

-- no debconf information



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