Upon further consideration, it looks to me like you might want to simply build a perl package with system constants, or use a system-wide configuration file, depending upon what precisely your application does.

Using shared memory is also an option if the name of the pipe will change, the server application will then write the filename of the pipe to shared memory with a pre-determined shared memory key, and the client will then read the value from shared memory. IPC::ShareLite may be all you need.