[Bulk] Re: The name "grep"

Polytropon freebsd at edvax.de
Tue Jul 8 00:31:30 UTC 2014

On Mon, 07 Jul 2014 18:28:01 +0200, Ralf Mardorf wrote:
> > On Mon, 07 Jul 2014 14:21:04 +0100, Arthur Chance wrote:
> > > 	dd [options] [ infile [ outfile ]]
> This way users by accident could mistake the infile with the outfile.
> We dislike to randomly screw up infile and outfile, so IMO it makes
> sense to force if= and of= "operands".

Because "man dd" says:

	The dd utility copies the standard input to the standard output.

Those are the "files" being used when no options are provided. To
override those defaults, if= and of= have to be supplied. It would
be comparable to having a -i and -o option (or like many other
programs do when _not_ using the defaults: -f, whereas the default
is usually program-specific, e. g. tar's default is /dev/sa0, or
$TAPE, if set).

Additionally, the form "command infile(s) outfile" is also found
in programs like cp or mv (or even ln), which do not require a
specific option for defining what is input and what is output.

Unlike JCL keyword parameters, we see positional parameters here,
which urges us to differentiate OS/JCL from DOS/JCL at the next
seizure of nostalgia. ;-)

However, dd is one of the few programs that causes touble with
traditional autocompleting shells, because '=' is a valid character
for use within file names, whereas ' ' (space) is the standard
delimiter character.

	% dd if=/dev/d[TAB]
	if=/dev/ not found
	% dd if=/dev/_

More intelligent shells however can deal with this. :-)

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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