How can I check if an argument is defined when starting/calling a batch file?

Question

I\'m trying to use the following validation logic in a batch file but the \"usage\" block never executes even when no parameter is supplied to the batch file.

Answer 1

The check for whether a commandline argument has been set can be [%1]==[], but, as Dave Costa points out, "%1"=="" will also work.

I also fixed a syntax error in the usage echo to escape the greater-than and less-than signs. In addition, the exit needs a /B argument otherwise CMD.exe will quit.

@echo off

if [%1]==[] goto usage
@echo This should not execute
@echo Done.
goto :eof
:usage
@echo Usage: %0 ^
exit /B 1