awk pipe and system call

i have two problems with awk:

first, the following works on my system, which shows system usage

    iostat 2 | awk '{print $1}'

However, the following seems never gets written to the log file

       iostat 2 | awk '{print $1}'  > log

It may gets buffered inside awk, is there a way to turn auto buffer
off?


Second problem is that I found it is impossible to send variables to
system calls:
the following works inside awk script:

       system( "echo " $0);

However, the following never works:

      BEGIN{ myvar1=0;}
      { myvar2 =1;
        system("echo " $myvar1  $myvar2);

Any ideas? thanks a bunch