China DOS Union

System: adv win2k
Goal to achieve: Synchronize files between two computers in the local area network. Then run the synchronized files.
There is a file xxx.exe in directory aaa on Computer A and it is shared.
Computer B can log in to Computer A (with username and password).
There is a file xxx.exe in directory BBB on Computer B.
Problem:
Now automatic login to Computer A has been achieved on Computer B and the shared directory is mapped as a drive letter R: on Computer B.
Now we want to perform copy if the file on Computer A is different from the file on local Computer B (just different dates are okay, and also copy if the file does not exist locally, both are xxx.exe). After copying, execute xxx.exe.
Now only a batch file is missing.
If there is a batch file, it can be combined with Windows scheduled tasks for full automation.
Which gentleman can write the batch file. Thanks in advance.
Can fc and comp be used! Please write the batch file. ------------
------------
Now it is achieved that the date of the file can be displayed using the statement for. That is, use for /f "skip=3" %a IN ('dir e:\a\xxx.exe' do @if exist %a echo %~ta
But how to compare. But I write these commands in the batch file and they are not correct. Who knows.
Always getting errors. But it is normal in the command line.
Depressed～～～

Keep up the good work. I finally succeeded.
Just why can't it be executed in the batch file.
It can be done in the command line. Why is that.
@echo off
if EXIST xxx.exe goto cmp
xcopy r:\aaa\xxx.exe
:cmp
for /f "skip=3" %%a IN ('dir r:\aaa\xxx.exe' do @if exist %%a set var1=%%~ta
for /f "skip=3" %%a IN ('dir xxx.exe' do @if exist %%a set var2=%%~ta
if %var1%==%var2% do goto end
copy r:\aaa\xxx.exe /yy
xxx.exe
:end
----------------
How can the if be used because there are spaces in var1.

Re: Expression:
　　To solve the space problem of var, you can add quotes on both sides of var1 and var2, just like
if "%var1%"=="%var2%" do goto end
This method is not applicable to win9x/dos6.xx (under its environment, you need to first output to a file, then use fc+find to judge).
Also: The do in your statement seems redundant. Try changing it to the following form:
if "%var1%"=="%var2%" goto end

Thanks to the person above. I'm really stupid myself