How do I make a batch file terminate upon encountering an error?

Check the errorlevel in an if statement, and then exit /b (exit the batch file only, not the entire cmd.exe process) for values other than 0.

same-executable-over-and-over.exe /with different "parameters"
if %errorlevel% neq 0 exit /b %errorlevel%

If you want the value of the errorlevel to propagate outside of your batch file

if %errorlevel% neq 0 exit /b %errorlevel%

but if this is inside a for it gets a bit tricky. You'll need something more like:

setlocal enabledelayedexpansion
for %%f in (C:\Windows\*) do (
    same-executable-over-and-over.exe /with different "parameters"
    if !errorlevel! neq 0 exit /b !errorlevel!
)

Edit: You have to check the error after each command. There's no global "on error goto" type of construct in cmd.exe/command.com batch. I've also updated my code per CodeMonkey, although I've never encountered a negative errorlevel in any of my batch-hacking on XP or Vista.

Here is a polyglot program for BASH and Windows CMD that runs a series of commands and quits out if any of them fail:

#!/bin/bash 2> nul

:; set -o errexit
:; function goto() { return $?; }

command 1 || goto :error

command 2 || goto :error

command 3 || goto :error

:; exit 0
exit /b 0

:error
exit /b %errorlevel%

I have used this type of thing in the past for a multiple platform continuous integration script.

One minor update, you should change the checks for "if errorlevel 1" to the following...

IF %ERRORLEVEL% NEQ 0 

This is because on XP you can get negative numbers as errors. 0 = no problems, anything else is a problem.

And keep in mind the way that DOS handles the "IF ERRORLEVEL" tests. It will return true if the number you are checking for is that number or higher so if you are looking for specific error numbers you need to start with 255 and work down.

I prefer the OR form of command, as I find them the most readable (as opposed to having an if after each command). However, the naive way of doing this, command || exit /b %ERRORLEVEL% is wrong.

This is because batch expands variables when a line is first read, rather than when they are being used. This means that if the command in the line above fails, the batch file exits properly, but it exits with return code 0, because that is what the value of %ERRORLEVEL% was at the start of the line. Obviously, this is undesirable in our script, so we have to enable delayed expansion, like so:

SETLOCAL EnableDelayedExpansion

command-1 || exit /b !ERRORLEVEL!
command-2 || exit /b !ERRORLEVEL!
command-3 || exit /b !ERRORLEVEL!
command-4 || exit /b !ERRORLEVEL!

This snippet will execute commands 1-4, and if any of them fails, it will exit with the same exit code as the failing command did.