This is an idea for an /etc/mailcap entry for "cat".  This allows a text
file to be catted with

    run-mailcap --action=cat foo.txt

The file below is debian/coreutils.mime and adding dh_installmime to the
binary-arch should install it to /usr/lib/mime/packages/coreutils.

I'm not sure why this would be useful. Why wouldn't you just pipe the
file to a pager and avoid the mailcap indirection? I'd think this would
be more likely to confuse people with control character output when
they're expecting an image or somesuch.

Mike Stone

Michael Stone <mstone@debian.org> writes:

Currently "run-mailcap --action=cat" cannot cat a text/plain text file
but adding a mailcap entry will let it work.

Primarily for genericness.  If you have a mail part or file then you let
run-mailcap find a good command.

But --action=cat is not for a pager, rather getting plain text to pass
on somewhere else.  For text/plain this is a no-op, but that knowledge
is not built-in to run-mailcap, hence a "cat" entry.  (Not hard-coding
it seems reasonable to me.  Let the runner be general and add entries
expressing what various programs like "cat" can or will do.  Other
programs might make use of those entries too.)

Oh, images or other binaries are meant to be crunched by the mailcap
rules to plain text for this --action=cat, or at least that's the idea.
For example xlhtml can crunch an application/excel to text (via html in
its case).  Or "tar" and 'unzip" offer a contents listing for tar and
zip files.

Kevin Ryde wrote:

I don't understand how mailcap and mime types are related to coreutils.
I don't think coreutils should own a mailcap entry.

What mail-user-agent are you using where this configuration is
advantageous?  I have used many MUAs over the years and this hasn't
ever been needed.  Therefore I am skeptical of the proposal.  I can
certainly use my MUA to perform actions on various sorts of text/*
attachments without this mailcap entry.  I am therefore suspicious
that this should actually be a wishlist enhancment request against
your MUA.

What specific action are you trying to do with what mailer that
currently isn't working for you?

The run-mailcap command is in the mime-support package.  Perhaps this
issue would be better discussed within the mime-support package
project rather than about coreutils?  It doesn't seem to me to be a
coreutils issue.

The text/plain mailcap is already loaded with other entries such as
on my system:

  text/plain; less '%s'; needsterminal
  text/plain; most '%s'; needsterminal
  text/plain; more '%s'; needsterminal
  text/plain; emacs23 %s; test=test -n "$DISPLAY"
  text/plain; emacs24 %s; test=test -n "$DISPLAY"
  text/plain; gedit --new-document %s; test=test -n "$DISPLAY"
  text/plain; gobby-0.5 %s; test=test -n "$DISPLAY"
  text/plain; gvim -f %s; test=test -n "$DISPLAY"
  text/plain; leafpad %s; test=test -n "$DISPLAY"
  text/plain; xfview %s; test=test -n "$DISPLAY"
  text/plain; xfwrite %s; test=test -n "$DISPLAY"
  text/plain; view '%s'; edit=vim '%s'; compose=vim '%s'; test=test -x /usr/bin/vim; needsterminal
  text/plain; gview -f '%s'; edit=gvim -f '%s'; compose=gvim -f '%s'; test=test "$DISPLAY" != ""
  text/plain; view '%s'; edit=vi '%s'; compose=vi '%s'; needsterminal

Those all seem more appropriate than 'cat'.

And more specifically 'cat' is not a display program.  It really
should be handled by a pager such as more, less or most.  (And those
already exist.)  Or at least a program that is designed to be a
display program.

I think this is definitely beyond the scope of the coreutils package.

Bob

Bob Proulx <bob@proulx.com> writes:

It was to make "run-mailcap --action=cat" work on text/plain.

Notice they're all either needsterminal or $DISPLAY, whereas the "cat"
program is a copiousoutput.

Perhaps, though it seemed to me reasonably clear the cat program could
be sensibly given an entry of the kind described in fact already in the
mailcap(5) man page.  mime-support generates a few things of its own
making, but mainly leaves entries to the package containing the program.

Kevin Ryde wrote:

A response that completely avoided answering my question.

The 'cat' program is for concatenating files.  It isn't a text display
program and should not be used as such.  Especially not as a system
default configuration.  (Nor should cat be used to write device
drivers in machine code even if one is inclined to do so.)

Bob