The TRUENAME command

Use the nearly undocumented DOS command TRUENAME to display the true name 
of a file on the screen. For example the command 

 
  truename c:\os2\dll\..\install\..\..\config.sys

will print C:\CONFIG.SYS to the screen. ("nearly undocumented" because 
TRUENAME /? works but you can't find anything about it in the online help) 
  

Source:  The OS/2 WARP Survival Guide 

  In OS/2 REXX programs you may use the function <STREAM with the third 
 parameter set to QUERY EXISTS to achieve the same result for existing 
 files.