unnamed pipe，批次獲取某資料夾下內的特定檔名，然後再批次做後續操作，如：

filename indata pipe "dir d:\sas\xml /b";

length fname $20.;

infile indata truncover;

input fname $20.;

call symput ("nvars",_n_);

run;

%macro want;

%do i=1 %to &nvars.;

data _null_;

if _n_=&i;

call symput ("file",fname);

run;

data tmp;

infile "d:\sas\xml\&file." firstobs=2;

input x y z;

run;

proc datasets;

append base=want data=tmp;

quit;

%end;

%mend;

%want