func Xargs(command string, args ...string) *XargsFilter {
	// Compute length of command+args
	base := len(command)
	for _, a := range args {
		base += 1 + len(a)
	}
	return &XargsFilter{
		command:    command,
		args:       args,
		limitArgs:  4096,
		limitBytes: 4096 - 100 - base, // Posix limit with slop
	}
}
func Xargs(command string, args ...string) *XargsFilter {
	// Compute length of command+args
	base := len(command)
	for _, a := range args {
		base += 1 + len(a)
	}
	return &XargsFilter{
		command:    command,
		args:       args,
		limitArgs:  4096,
		limitBytes: 4096 - 100 - base, // Posix limit with slop
	}
}
// Xargs returns a filter that executes "command args... items..."
// where items are the input to the filter.  The handling of items may
// be split across multiple executions of command (typically to meet
// command line length restrictions).  The standard output of the
// execution(s) is split into lines and the lines form the output of
// the filter (with trailing newlines removed).