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gearoid (1) [Avatar] Offline
In Unix scripts I can test a shell/environment variable thus:

if [ "$ENVVAR" = "" ]

This evaluates to TRUE if the variable does not exist or if it has no assigned value.

I find I cannot set an environment variable to the empty string using PowerShell on Win2000. Further no distinction is made between $ENVVAR and $EnvVar -- they are returned in UPPERCASE.

I have not found any documentation on this theme yet (although I am reading the In Action book at the moment).


PS> $env:myvar=""
PS> Get-ChildItem | Sort-Object -property name
lists current environment variables and their values but not "myvar"
Yet no error is thrown.

Any information welcome.