Tracing Batch Variable

Question

I have this batch which executes on the server computer. There is a scheduled job which runs the batch. The Batch detects a particular file and then it executes an sqlcmd like below:

if not exist %TRIG_FILE% goto No_Triggers

sqlcmd 
-S %WSL_SERVER% 
-d %WSL_DATABASE% 
-E 
-Q "DECLARE @RES integer;DECLARE @RET varchar(1);DECLARE @MSG varchar(65);EXEC Ws_Job_Release 1,'Release Job Unlock Batch','All',0,0,'Unlock_Batch',@RET OUTPUT,@MSG OUTPUT,@RES OUTPUT"

My question is - how did the batch know what the %WSL_SERVER% variable is, because when I look at the script, there is nowhere in there which sets the %WSL_SERVER% variable. This is the first time I'm reading a .bat script, I know a fair bit of programming, but I can't see how that variable was passed into this script so that it knows which server. There's no other batch calling this, it's from the batch run by the scheduler.

thanks

gemmo

Answer 1

Most likely the WSL_SERVER and WSL_DATABASE are global environment variables initialised every time with your Windows session. That means they exist (are defined) in every CMD session and thus in every batch script. You can open a new Command Prompt window and issue this command

SET WSL

which will (try to) display all environment variables, whether global or local, whose names start with WSL. My guess is the output will show you at least the two WSL variables used in your script.

There is a number of global variables pre-defined and maintained by the OS. Yours, however, are probably user-defined (just my guess based on the fact that my system does not have them). User-defined variables can be created by third-party software or your own (maybe someone else's) batch scripts, as well as with a standalone invocation of the SETX command:

SETX VarName "Value"

You can use that command to change the value of any of your variables globally. Note that you can also change that value temporarily only, for the duration of the script, using the SET command as usual, if global change is undesirable:

SET "VarName=Value"