How does SAS decide which file to select when using wildcards - import

Question

I have a SAS code that looks something like this:
DATA WORK.MY_IMPORT_&stamp;
INFILE "M:\YPATH\myfile_150*.csv"
delimiter = ';' MISSOVER DSD lrecl = 1000000 firstobs = 2 ignoredoseof;
[...]
RUN;
Now, at M:\YPATH I have several files named myfile_150.YYYYMMDD. The code works the way it is supposed to by importing always the latest file. I am wondering how SAS decides which file to choose, since the wildcard * can be replaced by anything. Does it sort the files in descending order and choose the first one?

Answer 1

On my system, SAS 9.4 TS1M4, SAS is reading ALL files that satisfy the wildcard.
I created 3 files (file_A.csv, file_B.csv, and file_C.csv). Each contain 1 record ('A', 'B', and 'C' respectively).
data test;
infile "c:\temp\file_*.csv"
delimiter = ';' MISSOVER DSD lrecl = 1000000 ignoredoseof;
format char $1.;
input char $;
run;
(Note I dropped the firstobs option from your code.)
The resulting TEST data set contains 3 observations, 'A', 'B', and 'C'.
This is the order of files returned when issuing
dir c:\temp\file_*.csv
SAS is using the default behavior of the OS and reading the files in that order.
25 data test;
26 infile "c:\temp\file_*.csv"
27 delimiter = ';' MISSOVER DSD lrecl = 1000000 ignoredoseof;
28 format char $1.;
29 input char $;
30 run;
NOTE: The infile "c:\temp\file_*.csv" is:
Filename=c:\temp\file_A.csv,
File List=c:\temp\file_*.csv,RECFM=V,
LRECL=1000000
NOTE: The infile "c:\temp\file_*.csv" is:
Filename=c:\temp\file_B.csv,
File List=c:\temp\file_*.csv,RECFM=V,
LRECL=1000000
NOTE: The infile "c:\temp\file_*.csv" is:
Filename=c:\temp\file_C.csv,
File List=c:\temp\file_*.csv,RECFM=V,
LRECL=1000000
NOTE: 1 record was read from the infile "c:\temp\file_*.csv".
The minimum record length was 1.
The maximum record length was 1.
NOTE: 1 record was read from the infile "c:\temp\file_*.csv".
The minimum record length was 1.
The maximum record length was 1.
NOTE: 1 record was read from the infile "c:\temp\file_*.csv".
The minimum record length was 1.
The maximum record length was 1.
NOTE: The data set WORK.TEST has 3 observations and 1 variables.
NOTE: DATA statement used (Total process time):
real time 0.04 seconds
cpu time 0.00 seconds