Hello, Paul,
this is correct, it is mentioned in grep --help. However, I always
expect the man pages to be more exhaustive. But here, it only says
grep searches the named input FILEs for lines containing a match to the
given PATTERN.  If no files are specified, or if the file “-” is given,
grep  searches  standard  input.   Bydefault, grep prints the matching
lines.
Well, of course, in the description of --recursive, it is mentioned:
      -r, --recursive              Read  all files under each
directory, recursively, following symbolic links only
if              they are on the command line.  Note that if no file
operand is given, grep searches              the working
directory.  This is equivalent to the -d recurse option.
This could be made a bit more consistent.
grep searches the named input FILEs for lines containing a match to the
given PATTERN.  If no files are specified, or if the file “-” is given,
grep  searches  standard  input or, by using the --recursive switch,
the current directory.   By default, grep prints the matching lines.
If I am the first in the world to fall for this, then please consider
this discussion as useless. This bug report is closed, anyway.
Kind regards,rexkogitans
Am Mittwoch, den 08.02.2017, 15:35 -0800 schrieb Paul Eggert:
> On 02/08/2017 01:12 PM, rexkogitans@gmx.at wrote:
> > Maybe this could be added in the man page.
> 
> It is already mentioned there, no? 'grep --help' says "With no FILE, 
> read . if a command-line -r is given, - otherwise." Perhaps the
> wording 
> could be improved; if so, specific wording suggestions would help.
>