如何告诉xargs选择哪个参数？

当xargs将第一个命令输出重定向到第二个命令的参数时，并且对于输出的哪个元素没有选择哪个参数，则只有一种方法，例如：

ls | xargs file  # there are as many arguments as files in the listing,
                 # but the user does not have too choose himself

现在，如果需要选择：

ls | xargs file | grep image | xargs mv.....   # here the user has to 
                                               # deal  with two arguments of mv, first for source second for destination, suppose your destination argument is set already by yourself and you have to put the output into the source argument. 

您如何告诉xargs将第一个命令的标准输出重定向到您选择的第二个命令的参数中？