CODEWITHSUNDEEP
batch-filebatch-processing
Saša Kalaba
Saša Kalaba

Reputation: 4421

Loop in batch not working

I've written a batch file that checks if only one instance of a server is running at any given time. The server is on a shared folder on a cloud, where multiple users have access to it.

If the server is running, a .txt file will be created, and as long as it's there, no one can start the server. When the server shuts down, the .txt file is deleted and another user is free to start it again.

minecraft_server.1.8.1.exe starts a Java process javaw.exe, which is the process that we need to monitor.

The code goes like this:

@echo off
IF EXIST *_RUNNING.txt (
    echo "ERROR, SERVER ALREADY RUNNING as %computername%"
    pause
    EXIT
) ELSE (
    copy NUL %computername%_RUNNING.txt 
    START /WAIT minecraft_server.1.8.1.exe
    tasklist /FI "IMAGENAME eq javaw.exe" 2>NUL | find /I /N "javaw.exe">NUL
:loop 
    IF "%ERRORLEVEL%"=="0" (
        TIMEOUT /t 60
        GOTO loop
    ) ELSE (
        del %computername%_RUNNING.txt
        echo "Server ended."
        pause
        EXIT 
    ) 
)

Everything works except the loop. It keeps returning ") was unexpected at this time". I'm new to writing batch files so please help.

Upvotes: 0

Views: 88

Answers (1)

Magoo
Magoo

Reputation: 80213

@echo off
IF EXIST *_RUNNING.txt (
echo "ERROR, SERVER ALREADY RUNNING as %computername%"
pause
EXIT
) 

copy NUL %computername%_RUNNING.txt 
START /WAIT minecraft_server.1.8.1.exe
:loop 
tasklist /FI "IMAGENAME eq javaw.exe" 2>NUL | find /I /N "javaw.exe">NUL
IF "%ERRORLEVEL%"=="0" (
TIMEOUT /t 60
GOTO loop
) 
del %computername%_RUNNING.txt
echo "Server ended."
pause
EXIT

Effectively, you have a label :loop in a block (a parenthesised sequence of statements) in your original. Labels terminate blocks.

With these modifications, the unnecessary else clauses have been removed. If batch exits or gotos then the else is not required - the next statements in the batch will be executed if the goto/exit doesn't happen.

Note that your label :loop is in the wrong place. As it stood, errorlevel would be established for the first and only invocation of tasklist. Thereafter, the loop would perpetually find errorlevel 0 if it was set to 0 on the first instance. Moving it to the indicated location would execute tasklist/find with a delay of 60 sec until errorlevel became non-zero, when the non-goto path to terminate the procedure would be taken.

(not tested, of course...)

Upvotes: 1

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