Batch file add/remove hosts file entries syntax error - dos

Question

The following script is supposed to manage adding and removing entries into the hosts file. Entries with .dev are supposed to point to localhost and all others should prompt for an IP address. If the entry already exists it should ask you if you want to remove it.
I am getting a vague The syntax of the command is incorrect error but I'm not sure which line it's referring to. If I turn #echo on it then spits out if ( on the next line and then dies. The only way I can catch the error is to do a screenshot because it immediately exits.
I've spent several hours on this, so any assistance would be greatly appreciated!
#echo off
title ClearSight Studio
echo Virtual website setup script
echo Version 1.4
echo Last modified 12/30/2011
echo.
REM Get the name of the domain name
echo What domain name? Ctrl+C to cancel. Example: newdomain.dev.
set /p domain= Domain:
REM Set a variable for the Windows hosts file location
set hostpath=\windows\system32\drivers\etc
set hostfile=hosts
set sitespath=\clearsight\sites
set extension=%domain:~-3%
REM Make the hosts file writable
attrib -r %hostpath%\%hostfile%
REM Add the domain to point to localhost at the end of the file if it doesn't already have an entry.
find /c " %domain%" %hostpath%\%hostfile%
if errorlevel 1 (
if /i %extension%==dev (
set /p ip= What is the IP?
)
echo. >> %hostpath%\%hostfile%
echo.# Adding %domain% via batch process on %date:~10,4%-%date:~4,2%-%date:~7,2%. >> %hostpath%\%hostfile%
if %ip% (
echo.%ip% %domain% >> %hostpath%\%hostfile%
) else (
echo.127.0.0.1 %domain% >> %hostpath%\%hostfile%
)
) else if errorlevel 0 (
echo Entry found in hostfile already. Would you like to remove it?
set /p remove= Remove (Y/N)
if /i %remove%==Y (
findstr /v "%domain%" %hostpath%\%hostfile% > %hostpath%\%hostfile%
)
)
if /i %extension%==dev (
REM Create the folder if it doesn't exist
if exist %sitespath%\%domain% (
echo %sitespath%\%domain% already exists.
) else (
echo Creating %sitespath%\%domain%...
mkdir %sitespath%\%domain%
)
)
REM Clean up
attrib +r %hostpath%\%hostfile%
echo.
echo Done.
if /i %extension%==dev (
REM Do a "git" of the repo, if requested
echo Would you like to clone an external git repository named %domain% from Bitbucket?
echo This assumes the git repository was set up under the "jamonholmgren" account.
echo Do it manually if it's under someone else's account. Also, make sure you have permissions to this repo.
set /p getgit= Get git clone? (Y/N):
)
REM
if /i %getgit%==Y (
git clone git#bitbucket.org:jamonholmgren/%domain%.git %sitespath%\%domain%\
pause
) else (
echo Okay, then we're done.
pause
)

Answer 1

You have two problems with this bit of code
if %ip% (
echo.%ip% %domain% >> %hostpath%\%hostfile%
) else (
It is invalid syntax. I presume you want to test if the variable is defined. The proper syntax is if defined ip (
You are attempting to expand %ip% in the same if() block where it was defined. This can't work because %ip% is expanded at parse time, which is before you assign the value! The solution is to use delayed expansion instead !ip!. Delayed expansion must first be enabled, probably near the top of your script, using setlocal enableDelayedExpansion
So the fixed code would look something like this
setlocal enableDelayedExpansion
.
.
.
if defined ip (
echo.!ip! %domain% >> %hostpath%\%hostfile%
) else (
You have the same delayed expansion issue with %remove%
Edit - expanding on Andriy M's comment
You also have a potential issue with how you deal with user input for ip and remove. Both values should be initialized either to nothing, or to a default value, prior to prompting for the value. If the user does not enter anything, then the existing default value (if any) is preserved.
Also, you may want to confirm that a valid value was entered, especially for the ip. If you do, then you will want to take the prompt out of the loop and put it in a called subroutine. The subroutine can check if a value was entered and loop back to try again if it wasn't. It must be in a subroutine because you cannot GOTO within a parenthesized block of code like you have with your IF statement.

Answer 2

When you expand a variable value via %variable% its value is expanded just once after the line that contain commands is read and before the commands are executed. For example:
set var=Original
set var=New & echo %var%
Previous line show "Original". The same effect happen with any command enclosed in parentheses (that belong to any IF or FOR commands).
The way to solve this problem is using Delayed Variable Expansion by enclosing a variable in exclamation marks instead percents:
set var=Original
set var=New & echo !var!
However, you must first activate the delayed expansion with this command:
setlocal EnableDelayedExpansion
So, insert previous line at beginning of your program and change ALL references to variables that may change its value inside an IF or FOR by !name! instead of %name%. For example:
if %ip% (
that I'm sure is the line that caused your problem...

Answer 3

Thanks everyone for the help! Here is the final (working) result in case anyone ever wants to do something similar. The output to the screen could probably use a little tweaking but in all my testing it seems completely reliable.
#echo off
setlocal enableDelayedExpansion
title ClearSight Studio
echo Virtual website setup script
echo Version 1.5
echo Last modified 2/23/2012
echo.
REM Get the name of the domain name
echo What domain name? Ctrl+C to cancel. Example: newdomain.dev.
set /p domain= Domain:
REM Set a variable for the Windows hosts file location
set hostpath=\windows\system32\drivers\etc
set hostfile=hosts
set sitespath=\clearsight\sites
set extension=%domain:~-3%
REM Make the hosts file writable
attrib -r %hostpath%\%hostfile%
REM Add the domain to point to localhost at the end of the file if it doesn't already have an entry.
find /c " %domain%" %hostpath%\%hostfile%
if errorlevel 1 (
if /i NOT %extension%==dev (
set /p ip= What is the IP?
) else (
set ip=127.0.0.1
)
echo. >> %hostpath%\%hostfile%
echo.# Adding %domain% via batch process on %date:~10,4%-%date:~4,2%-%date:~7,2%. >> %hostpath%\%hostfile%
echo.!ip! %domain% >> %hostpath%\%hostfile%
) else if errorlevel 0 (
echo Entry found in hostfile already.
set /p remove= Would you like to remove it? (Y/N)
if /i !remove!==Y (
findstr /v %domain% %hostpath%\%hostfile% > %hostpath%\%hostfile%.txt
type %hostpath%\%hostfile%.txt > %hostpath%\%hostfile%
)
)
if /i %extension%==dev (
REM Create the folder if it doesn't exist
if exist %sitespath%\%domain% (
echo %sitespath%\%domain% already exists.
) else (
echo Creating %sitespath%\%domain%...
mkdir %sitespath%\%domain%
)
)
REM Clean up
attrib +r %hostpath%\%hostfile%
REM Flush DNS so the changes are available imidiately
ipconfig /flushdns
echo.
echo Done.
if /i %extension%==dev (
REM Do a "git" of the repo, if requested
echo Would you like to clone an external git repository named %domain% from Bitbucket?
echo This assumes the git repository was set up under the "jamonholmgren" account.
echo Do it manually if it's under someone else's account. Also, make sure you have permissions to this repo.
set /p getgit= Get git clone? (Y/N)
)
REM
if /i !getgit!==Y (
git clone git#bitbucket.org:jamonholmgren/%domain%.git %sitespath%\%domain%\
pause
) else (
echo Okay, then we're done.
pause
)

Answer 4

Just some hints for debugging the batch file:
Start it from a cmd shell to avoid closing the window after exiting
Add more REM commands that will serve as log entries when turning echo on
Simplify your script by repeatedly removing parts from the end until it runs without error. Reinsert the faulty parts and try to figure out what's wrong there
While this does not quite answer your question, I hope the hints will help you solve the problem. You are always welcome to ask for general advice, but I'm afraid that your particular problem is somehow a bit too specific to be of general interest.