欲把当前目录下的file1.txt复制为file2.txt，正确的命令是

欲把当前目录下的file1.txt复制为file2.txt，正确的命令是
A.copyfile1.txtfile2
B.cpfile1.txt|file2.txt
C.catfile2.txtfile1
D.catfile1.txt>file2.txt
正确答案：D