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Undocumented

What's your Truename




DOS version 4.0 added an undocumented command to its list. TRUENAME. This command would return the actual Truename of the file. For instance, if you used

  SUBST G: C:\TEMP\BAK
so that any file in this directory could be accessed
  G:FILE1.BAK
and issued the command
  TRUENAME FILE1.BAK
DOS would return
  C:\TEMP\BAK\FILE1.BAK



Along with the TRUENAME command came the DOS interrupt service. Service 60h. However, this interrupt service was included with DOS 3.0. Here are the register uses:
 On entry:
   AH = 60h
   DS:SI -> ASCIZ filename or path
   ES:DI -> 128-byte buffer for truename

 Return:
   CF set on error
      AX = error code
   CF clear if successful
      ES:DI -> 128-byte buffer of truename
Try it out. See what you come up with. ¥


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