First of all Thanking you for your very helpful reply, but may i ask a related question that:Hello.
Okay, here follows a try of a simple descrition for you:
If you run a commandand that produce an output (result of the programm) and you want to use this output as input (argument) for an other command, you can perform this task with xargs in one step. By default xargs use 'echo' as command to write the result on standard output.
Thats the main purpose of it.
command1 (produce an output ->) | xargs [options] command2 (<- take the output of command1 as input)
For more you realy must read intensive the manpage. There are more complexe ability of xargs, but so i hope you now can understand the base of the xargs usage.