We help IT Professionals succeed at work.

Check out our new AWS podcast with Certified Expert, Phil Phillips! Listen to "How to Execute a Seamless AWS Migration" on EE or on your favorite podcast platform. Listen Now


MS-DOS SET Statement Withing the IF Clause

grishkin1 asked
Medium Priority
Last Modified: 2012-05-04
I have the following code:

@SET Description=BEFORE
@IF 0 EQU 0 (
@SET Description=AFTER
@ECHO The curent state is %Description% the IF statement.
@ECHO The curent state is %Description% the IF statement.

When I run it, it returns:
The curent state is BEFORE the IF statement.
The curent state is AFTER the IF statement.

How do I make it return the second output only, in other words, how do make the first ECHO display the "AFTER" note?

Watch Question


"@IF 0 EQU 0"

since it's always true, so the code inside will be executed anyway. you may change it to

"@IF 0 EQU 1" or whatever, but not '0'. the code inside bracket won't be executed.

Top Expert 2007
Unlock this solution with a free trial preview.
(No credit card required)
Get Preview

Hi grishkin1,
You need to enable delayed environment variable expansion for this to work.

From "set /?":

----start quote---
Finally, support for delayed environment variable expansion has been
added.  This support is always disabled by default, but may be
enabled/disabled via the /V command line switch to CMD.EXE.  See CMD /?

Delayed environment variable expansion is useful for getting around
the limitations of the current expansion which happens when a line
of text is read, not when it is executed.  The following example
demonstrates the problem with immediate variable expansion:

    set VAR=before
    if "%VAR%" == "before" (
        set VAR=after
        if "%VAR%" == "after" @echo If you see this, it worked

would never display the message, since the %VAR% in BOTH IF statements
is substituted when the first IF statement is read, since it logically
includes the body of the IF, which is a compound statement.  So the
IF inside the compound statement is really comparing "before" with
"after" which will never be equal.  Similarly, the following example
will not work as expected:

    set LIST=
    for %i in (*) do set LIST=%LIST% %i
    echo %LIST%

in that it will NOT build up a list of files in the current directory,
but instead will just set the LIST variable to the last file found.
Again, this is because the %LIST% is expanded just once when the
FOR statement is read, and at that time the LIST variable is empty.
So the actual FOR loop we are executing is:

    for %i in (*) do set LIST= %i

which just keeps setting LIST to the last file found.

Delayed environment variable expansion allows you to use a different
character (the exclamation mark) to expand environment variables at
execution time.  If delayed variable expansion is enabled, the above
examples could be written as follows to work as intended:

    set VAR=before
    if "%VAR%" == "before" (
        set VAR=after
        if "!VAR!" == "after" @echo If you see this, it worked

    set LIST=
    for %i in (*) do set LIST=!LIST! %i
    echo %LIST%

----end quote----

This should work as you expect:

@echo off
SET Description=BEFORE
IF 0 EQU 0 (
    SET Description=AFTER
    ECHO The curent state is !Description! the IF statement.
ECHO The curent state is %Description% the IF statement.

:) sorry Steve.
Top Expert 2007

No problem. You are the master of delayed environment variable expansion.

Last night I was looking at one of your previous submissions to figure out how to utilize an environment variable in a set substrings.


Wow!  Thanks, Steve!  It worked!  You're da man! :)

Hi all,
after reading the post, I think I misunderstood the question. Because English is not my first language. Sorry about my post.

Top Expert 2007

Greetings grishkin1 - if you're all set here, can you close out this question?
See http:help.jsp#hs5 for assistance on closing.

Unlock the solution to this question.
Thanks for using Experts Exchange.

Please provide your email to receive a free trial preview!

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.


Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.