On 11/18/2016 10:43 PM, 積丹尼 Dan Jacobson wrote:
> The example is confusing, as it just happens to result in 1 2 3,
>
> $ printf '%s\n' 1 2 3 4 > file1
> $ printf '%s\n' 2 3 4 5 6 > file2
> $ comm --total -123 file1 file2
> 1 2 3 total
>
> So please use
>
> $ printf '%s\n' 0 2 3 5 6 > file1
> $ printf '%s\n' 1 2 4 6 7 8 9 > file2
> $ comm --total -123 file1 file2
> 3 5 2 total
I see the point. I changed the example data to 'a b c ...' which I think
is even easier to read and understand.
> Also add a note "However --total is a GNU extension. For a portable way
> to make totals, use wc:
>
> $ echo Lines only in 1st = $(comm -23 file1 file2 | wc -l)
> $ echo Lines only in 2nd = $(comm -13 file1 file2 | wc -l)
> $ echo Lines in both = $(comm -12 file1 file2 | wc -l)
I'll squash in the attached, and push soon.
Thanks & have a nice day,
Berny
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 21fa2be..b0c13b9 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -5147,14 +5147,32 @@ The delimiter @var{str} may not be empty.
@item --total
Output a summary at the end.
+Similar to the regular output,
+column one contains the total number of lines unique to @var{file1},
+column two contains the total number of lines unique to @var{file2}, and
+column three contains the total number of lines common to both files,
+followed by the word @samp{total} in the additional column four.
+
In the following example, @command{comm} omits the regular output
(@option{-123}), thus just printing the summary:
@example
-$ printf '%s\n' 1 2 3 4 > file1
-$ printf '%s\n' 2 3 4 5 6 > file2
+$ printf '%s\n' a b c d e > file1
+$ printf '%s\n' b c d e f g > file2
$ comm --total -123 file1 file2
-1 2 3 total
+1 2 4 total
+@end example
+
+This option is a GNU extension. Portable scripts should use @command{wc} to
+get the totals, e.g. for the above example files:
+
+@example
+$ comm -23 file1 file2 | wc -l # number of lines only in file1
+1
+$ comm -13 file1 file2 | wc -l # number of lines only in file2
+2
+$ comm -12 file1 file2 | wc -l # number of lines common to both files
+4
@end example
@optZeroTerminated
