Disable comments in stdout (DOS)

If I use Dos command "copy" to concatenate two files:

copy a1.txt + a2.txt a.txt

开发者_StackOverflow社区I will have something like the following in stdout:

C:\a1.txt
C:\a2.txt
   1 file(s) copied.

I do not want to have anything written in stdout, I mean, I just want to have 'a.txt' without those 3 lines written in stdout. Is there any way to do so? the reason is, I need speed and I know that any IO takes time.

Thanks, Shadi.

Redirect output to nul: copy a1.txt+a2.txt a.txt > nul.