Raise error in SAS EG - sas

Question

I have a SAS EG program that checks if a file exists and refuses to replace it if it dose exists.
When this happens I want SAS EG to show an error on that program and display a meaningful custom error message in the log. And I want the error message to look the same as other error messages people are used to seeing in the log so they pay attention to it.
For now I have just imported a file with a name of my error message. This is not great because it appends file not found messages to the message I want to display.
Is there any way I can declare that there is an error and provide an error message to put in the LOG

Answer 1

The SAS log uses a very simple way to change text color: the first word in the line of text to display in the log. You can recreate ERROR, WARNING, and NOTE messages in both %put and put statements.
%put NOTE: This is a note;
%put WARNING: This is a warning;
%put ERROR: I AM ERROR;
For example, let's say you want to display an error if a certain value is missing.
data have;
input var;
datalines;
1
.
2
3
.
;
run;
%put NOTE: Now checking for missing values...;
data _null_;
set have;
if(missing(var) ) then
put 'ERROR: A missing value for "var" was found at observation ' _N_;
run;
You can also do this with macros, such as creating a flag during certain check steps, or using the &syserr automatic macro variable.
%macro check;
%let e = 0;
data _null_;
set have;
if(missing(var) ) then call symput('e', 1);
run;
%if(&e) %then %put ERROR: An error was found.;
%mend;