%let dirname = c:\work\raw_data_files;
filename DIRLIST pipe "dir /B &dirname\*.txt";
data dirlist ;
     length fname $256;
     infile dirlist length=reclen ;
     input fname $varying256. reclen ;
run;
proc print data = dirlist;
run;
data all_text (drop=fname);
  length myfilename $100;
  length name $25;
  set dirlist;
  filepath = "&dirname\"||fname;
  infile dummy filevar = filepath length=reclen end=done missover;
  do while(not done);
    myfilename = filepath;
    input name $  x1 x2 x3;  
    output;
  end;
run;
proc print data=all_text;
run;