How to use "svn export" command to get a single file from the repository?

For the substition impaired here is a real example from GitHub.com to a local directory:

svn ls https://github.com/rdcarp/playing-cards/trunk/PumpkinSoup.PlayingCards.Interfaces
svn export https://github.com/rdcarp/playing-cards/trunk/PumpkinSoup.PlayingCards.Interfaces /temp/SvnExport/Washburn

See: Download a single folder or directory from a GitHub repo for more details.

You don't have to do this locally either. You can do it through a remote repository, for example:

svn export http://<repo>/process/test.txt /path/to/code/

Guessing from your directory name, you are trying to access the repository on the local filesystem. You still need to use URL syntax to access it:

svn export file:///e:/repositories/process/test.txt c:\test.txt