求下面的make怎么理解

make $1 -j4 2>&1

-j4是双核同时make

2>&1怎么理解？

>&p                     The  output  to  the  co-process  is
                             moved to standard output.

     If one of the above is preceded by a digit,  then  the  file
     descriptor number referred to is that specified by the digit
     (instead of the default 0 or 1). For example:

     ... 2>&1

     means file descriptor 2 is to be opened  for  writing  as  a
     duplicate of file descriptor 1.

     The order in which redirections are  specified  is  signifi-
     cant.  The  shell evaluates each redirection in terms of the
     (file descriptor, file) association at the time  of  evalua-
     tion. For example:

     ... 1>fname 2>&1

情查看精华帖中的 输出重定向

thanks