FTAM/9000 User's Guide

Chapter 4 63
Special FTAM Files
FTAM Shadow Files
FTAM Shadow Files
The FTAM Virtual File Store (VFS) is defined by the FTAM ISO
standard, and provides a common file system abstraction for all FTAM
implementations to use. Each vendor independently maps the FTAM
VFS to their real file system.
The FTAM VFS defines several file attributes—including access control
mechanisms—that are not native to HP-UX. (See Chapter 5, “FTAM File
Protection.”) To implement these attributes and mechanisms, HP-UX
FTAM uses supplemental files called shadow files.
When FTAM creates or modifies an HP-UX file, it creates a shadow file
for the HP-UX file. The shadow file has the same name as the HP-UX
file, prefixed by a period and underscore (“._”). The shadow file is located
in the same directory as the HP-UX file.
For example, suppose you use the fcp command to copy a file named
“mydata” from a remote host to your home directory. If you list the whole
directory (use $ ls -a), you will find both of the following files:
._mydata mydata
The file named ._mydata is the FTAM shadow file for the file named
mydata.
FTAM must be able to handle new files, which have no shadow file, as
well as existing files.
• If FTAM attempts to create or modify a file for which there is a
shadow file, it applies the attributes and access control settings noted
in the shadow file.
• If FTAM attempts to create or modify a file for which there is no
shadow file, it applies the default attributes and access control
settings noted in Chapter 7, “FTAM File Details.” FTAM creates a
new shadow file, which contains these defaults.