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JackPGreen
JackPGreen

Reputation: 1139

Difference when executing Java command via CMD vs Powershell - caused by periods (".")

I've got an example Java application that requires an HTTP Proxy to be specified in some environments.

When I try running this using the argument as suggested on the Oracle website in CMD (Command Prompt) it works fine.

E:\>java -Dhttp.proxyHost=http://proxy.example.com -jar myJAR.jar
System properties...
[...]
http.proxyHost=http://proxy.example.com

You can see that the application has been run, and when listing the system properties it's correctly received the http.proxyHost property.

However, when I run this from Powershell, I get the following:

Windows PowerShell
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Try the new cross-platform PowerShell https://aka.ms/pscore6

PS E:\> java -Dhttp.proxyHost=http://proxy.example.com -jar myJAR.jar
Error: Could not find or load main class .proxyHost=http:..proxy.example.com

Here it appears some kind of breaking has occurred around the first "." and from then on it's treated the rest as another argument.

If the argument is quoted - e.g. -D"http.proxyHost"=http://proxy.example.com - then it works fine in Powershell.

Can anyone explain this behavior, please?

Upvotes: 2

Views: 418

Answers (2)

mklement0
mklement0

Reputation: 439367

Unfortunately, you're seeing a bug in PowerShell, present up to at least v7.3.6 (current as of this writing):

Something that looks like a parameter to PowerShell is broken into two arguments at the . (period) - even though the argument should simply be passed through, given that an external program is called - see GitHub issue #6291; in your case, -Dhttp.proxyHost=http://proxy.example.com is unexpectedly passed as
-Dhttp .proxyHost=http://proxy.example.com (note the space before the .)

Workarounds:

  • `-escape the initial - (or quote the . character individually ('.') or quote the whole argument):

    java `-Dhttp.proxyHost=http://proxy.example.com -jar myJAR.jar

  • Alternatively, as shown in Sergey Shu's answer, use --%, the stop-parsing symbol, to force PowerShell to pass all arguments through without applying PowerShell's usual parsing rules.

    • Caveat: Use of --% has major side effects, notably the inability to use variable references in the command and the inability to apply redirections - see this answer for details.

Upvotes: 1

Sergey Shu
Sergey Shu

Reputation: 11

man about_Parsing

try running from powershell using --% parameter:

java --% -Dhttp.proxyHost=http://proxy.example.com -jar myJAR.jar

Upvotes: 1

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