The command interpreter
cmd.exe has a concept
known as the error level,
which is the exit code of the program most recently run.
You can test the error level with the
IF ERRORLEVEL command:
IF ERRORLEVEL 1 ECHO error level is 1 or more
IF ERRORLEVEL n test succeeds
if the error level is n or more.
This was presumably because there were programs that
expressed different degrees of failure with higher and
higher exit codes.
For example, the
diff program has three exit codes:
0 means the files are the same;
1 means the files are different;
2 means that something terrible happened.
There are also programs that use an exit code of zero
to mean success and anything else to mean failure.
In addition to this internal state,
you can, if you wish, create an environment variable
with the name
in the same way that you can create an environment variable
But, as with
that variable won’t have any effect on the error level.
rem this next command sets the error level to zero CMD /C EXIT 0 set ERRORLEVEL=1 if ERRORLEVEL 1 echo Does this print?
The message is not printed because the
environment variable has no effect on the error level.
It’s just a variable whose name happens to coincide with a command
“Hey, when I tried to withdraw the money, I got an insufficient funds error. What am I doing wrong?”
Now, it does happen to be the case that if command extensions are
enabled and you say
%ERRORLEVEL%, then the command processor first looks
for an environment variable called
and if it can’t find one, then it replaces
with the current value of the internal error level value.
It’s a fallback step,
in the same way that your neighbor is a fallback delivery location if
you aren’t home.
If you file a change-of-address form for yourself, that doesn’t affect
packages sent to your neighbor.
The same behavior can be seen with
If you did not explicitly set an environment variable called
%CD% expands to the command processor’s current
But you can’t change directories by saying
I can think of a few reasons why this feature may have been added.
- So you can include the error level in a log file:
ECHO error level is %ERRORLEVEL%>logfile
- So you can perform other types of tests against the error level,
for example, to perform an equality test:
IF %ERRORLEVEL% EQU 1 echo Different!
But I’m digressing.
My point for today is that the error level is not the same
ERRORLEVEL environment variable.