Where does GOTO :EOF return to? - batch-file

Question

I'm trying to understand where in the code exactly does GOTO :EOF return to?
Here is the code:
SET count=1
FOR /f "tokens=*" %%G IN (somefile.txt) DO (call :subroutine "%%G")
GOTO :EOF
:subroutine
echo %count%:%1
set /a count+=1
GOTO :EOF

Answer 1

:EOF is a predefined label as Microsoft explains in documentation for command GOTO. The help output by running in a command prompt window goto /? explains also this special label for End Of File. But this predefined label is supported only with command extensions being enabled as by default.
The help output by running in a command prompt window call /? and of course also the documentation for command CALL explain both that goto :EOF should be used to exit a subroutine called with call :Label.
A subroutine is nothing else than another batch file embedded within current batch file called with command call. If the subroutine is at end of the batch file, real end of file marks the end of the subroutine.
But there can be multiple subroutines in a batch file.
So a command is needed for command interpreter to exit the subroutine on reaching a specific line in command processing and go back to the calling command line. goto :EOF as well as exit /B can be both used everywhere to either exit a subroutine or exit the current batch file processing.
In batch code in question the first goto :EOF is needed to exit batch file processing without an unwanted fall through to the subroutine code after finishing the loop.
The second goto :EOF in batch code of questioner is for exiting the subroutine and continue processing in FOR loop in second line. It does not exit processing of the batch file, it exits only the processing of the subroutine.
Note 1: goto EOF without a colon requires that there is really a line starting with :EOF in the batch file, i.e. the label EOF must exist in the file. goto :EOF always results in exiting subroutine/batch processing with command extensions enabled even if there is a label EOF in the batch file because of a line starting with :EOF.
Note 2: Command EXIT without parameter /B results always in exiting entire command process independent on calling hierarchy and independent on how the Windows command processor was started – with parameter /K to keep cmd.exe running as used when opening a command prompt window or with /C to close after command processing finished as used on double clicking a batch file. Therefore exit without /B should be used wisely in a batch file (best: never).
Note 3: exit /B without or with an exit code works always, but outputs an error message with command extensions disabled as demonstrated by this code:
#echo off
setlocal DisableExtensions
echo Use command exit /B with command extensions disabled.
exit /B 5
echo This line is not processed anymore.
Executing this batch file from within a command prompt window results in output of the error message:
The system cannot find the batch label specified - EOF
But the processing of the batch file is exited nevertheless with the exit code value 5 as it can be seen on running next in same command prompt window echo ERRORLEVEL is: %ERRORLEVEL% which outputs: ERRORLEVEL is: 5
It looks like there is assigned first the specified exit code value 5 to the dynamic variable ERRORLEVEL on using exit /B 5 and next is executed goto :EOF because of option /B. That fails because of disabled command extensions resulting in the error message and in exiting the batch file processing as it always occurs on a label to go to does not exist in a batch file.
In other words exit /B without or with an additional exit code always works, but there should be appended 2>nul to suppress the error message on command extensions disabled, i.e. use exit /B 2>nul (without exit code) or exit /B 5 2>nul (with exit code)
Note 4: ERRORLEVEL is not affected by goto :EOF, but the Microsoft GOTO documentation is mute on this topic. exit /B # sets ERRORLEVEL to # as documented by Microsoft. exit /B # can be also used instead of goto :EOF to exit a subroutine with a specific exit code evaluated on the command line calling the subroutine like on using the operators && or || or on next command after calling command line with if errorlevel X. However, explicitly exiting a batch file or a subroutine with a specific exit code is usually not needed as neither goto :EOF nor exit /B modify the current value of ERRORLEVEL.
Note 5: Do not use goto:EOF or call:Label in a batch file with no space between command GOTO respectively CALL (argument 0) and the label (argument 1). There should be always used goto :EOF and call :Label with a space as argument strings separator between command and label. The reason is that goto:EOF results in the attempts to find in current directory first a file with name goto: and next a file with name goto:EOF. The incorrect command call:Label results in searching for a file with name call: and next with name call:Label. The file system returns for both syntactically wrong commands twice to cmd.exe that the name is invalid. Then cmd.exe detects the colon as reason for the invalid name and splits the command up into command and label argument and finally runs the command with success. The usage of goto :EOF and call :Label does not cause any wrong file system accesses as cmd.exe immediately recognizes the string goto respectively call as internal command.
For details on ERRORLEVEL behavior see:
What are the ERRORLEVEL values set by internal cmd.exe commands?
Which cmd.exe internal commands clear the ERRORLEVEL to 0 upon success?
Single line with multiple commands using Windows batch file

Answer 2

GOTO :EOF is functionally equivalent to exit /B, but both forms only works when Extensions are enabled. The test for this point is very simple:
setlocal DisableExtensions
goto :EOF
Compare previous code vs. this one:
setlocal DisableExtensions
exit /B
This means that GOTO :EOF returns to the same point where exit /B would return.

Answer 3

:eof means "End of file". It's used to make the script finish without executing any of the commands below.

Answer 4

As the GOTO and CALL are using the same functionality to find a label you have an option to access the :EOF with CALL too:
CALL ::EOF
Same as GOTO (when CALL with the additional semicolon) the actual end-of-file will be the preferable point where the flow of the script will go. If you have your own label\function defined with EOF you can access it with single semicolon.
Though calling the :EOF has no much use - you can't put a code after the end of file so this line is actually doing nothing (though this will hit the performance as the end of file is parsed). And as GOTO and EXIT /B this wont work without enabled extensions.