How to change ${USER} variable in IntelliJ IDEA without changing OS user name?

You can modify the file idea.exe.vmoptions or idea64.exe.vmoptions, which should be in the bin folder of your IDE installation. For linux version, it could be idea.vmoptions. You need to add there a parameter:

-Duser.name=YOURNAME

How to open the file:

• Ctrl+Shift+A > type "vm options" > select option
• Help > Edit custom VM options...

This would make your ${USER} variable inside IntelliJ Idea equals to parameter value and you don't have to change the current OS user login name. I've just tested it in the IntelliJ Idea 14.1.3 with file and code templates.

To change the ${USER} variable for just the current user (rather than system wide) select Help->Edit Custom VM Options and add the following to the file that opens in your editor:

-Duser.name=USER

Then save the file and restart your editor.

https://intellij-support.jetbrains.com/hc/en-us/articles/206544869-Configuring-JVM-options-and-platform-properties