Re: [bug #24974] Document that comm's option "-1", "-2" and "-3" can be combined

[Pádraig Brady]

anonymous wrote:
> URL:
>   <http://savannah.gnu.org/bugs/?24974>
> 
> Hello,
> 
> Could you explicitly document that "-1", "-2" and "-3" options
> of "comm" can be combined.
> This isn't obvious, and may lead some people [me!] to use
> other tools instead.

It's common for options to be combined unless otherwise stated,
but I take your point that it's perhaps a little confusing.
Perhaps this change would make it more obvious?
It's not removing info as the info removed is already
presented on the previous line.

diff --git a/src/comm.c b/src/comm.c
index 4ec7e4a..6f250a9 100644
--- a/src/comm.c
+++ b/src/comm.c
@@ -113,9 +113,9 @@ and column three contains lines common to both files.\n\
 "), stdout);
       fputs (_("\
 \n\
-  -1              suppress lines unique to FILE1\n\
-  -2              suppress lines unique to FILE2\n\
-  -3              suppress lines that appear in both files\n\
+  -1              suppress output of column 1\n\
+  -2              suppress output of column 2\n\
+  -3              suppress output of column 3\n\
 "), stdout);
       fputs (_("\
 \n\


I might add some examples to the docs also, along the lines
of the following if I get a second. At least I should get
the docs for `comm` and `join` to reference each other.

# set operations on sorted files

comm file1 file2 | sed 's/^\t*//'     #Union
comm -12 file1 file2                  #Intersection
comm -13 file1 file2                  #Difference
comm -3 file1 file2 | sed 's/^\t*//'  #Symmetric Difference

join -a1 -a2 file1 file2              #Union
join file1 file2                      #Intersection
join -v2 file1 file2                  #Difference
join -v1 -v2 file1 file2              #Symmetric Difference

# set operations on unsorted files

sort file1 file2 | uniq               #Union
sort file1 file2 | uniq -d            #Intersection
sort file1 file1 file2 | uniq -u      #Difference
sort file1 file2 | uniq -u            #Symmetric Difference

cheers,
Pádraig.

p.s. Those new --check-order --nocheck-order options confuse me.
When they were added I only took a quick look at the implementation
rather than the interface (which Bo Borgerson kindly sped up for us).
Perhaps something like this would be clearer:

  --check-order={none,mismatch,unsorted}
  By default --check-order=mismatch is enabled.

I suppose it's too late to change now.