Write system date and time as string to gdx

Question

I want to store the system date and time as a string to gdx when executing a script, preferably with a custom format.

I tried the following:

parameter 
    exec_date   execution date
    exec_time   execution time
;

exec_date =  '%system.date1%';
exec_time =  '%system.time%';

However I get the following error message in the .lst file:

   1  parameter
   2          exec_date       execution date
   3          exec_time       execution time
   4  ;
   5   
   6  exec_date =  'Dec 17, 2020';
****               $119,140,409
**** 119  Number (primary) expected
**** 140  Unknown symbol
**** 409  Unrecognizable item - skip to find a new statement
****        looking for a ';' or a key word to get started again
   7  exec_time =  '13:24:05';
****               $119,409
**** 119  Number (primary) expected
**** 409  Unrecognizable item - skip to find a new statement
****        looking for a ';' or a key word to get started again

The following snippet gives the same error message:

variable
    exec_date   execution date
    exec_time   execution time
;

exec_date =  '%system.date1%';
exec_time =  '%system.time%';

Finally, the following snippet runs without error:

$set exec_date = '%system.date1%';
$set exec_time = '%system.time%';

However it seems that both exec_date and exec_time are not dumped to gdx:

gams date gdx=date

Moreover, I tried to display exec_date and exec_time:

display 
    exec_date
    exec_time;

However, I get the following error message in the .lst file:

  21  display
  22          exec_date
****                  $140
**** 140  Unknown symbol
  23          exec_time;
****                  $140
**** 140  Unknown symbol

Is it possible to store the system date and time as a string to gdx?

Moreover, is it possible to format the date string as yyyy-mm-dd?

Answer 1

It can be implemented as set:

set
    exec_date   /'%system.date%'/
    exec_time   /'%system.time%'/
;

display 
    exec_date
    exec_time
;

This outputs:

----     31 SET exec_date  

12/17/20


----     31 SET exec_time  

15:32:46

And is saved to gdx using

gams date gdx=date