SCO OpenServer支持Versioning Filesystems(undelete),但是缺省卻沒有打開此項功能，
下面是具體細節：
1) scoadmin中選擇Hardware/Kernel Manager，選擇Filesystem configuration，
設置MAXVDEPTH為一個非零值(n=保存多少以前版本，設置較大數時要考慮磁盤空間)
設置MINVTIME(文件versioned之前等待的秒數)
2) 重新編譯(Relink)內核；
3) 重新啟動服務器；
4) 啟用Undelete，針對需要設置undelete的目錄(例如:/u/data)
undelete -s /u/data
5) 為了察看Versioned情況,設置以下環境變量：
SHOWVERSIONS=1; export SHOWVERSIONS
6) 用文件察看命令察看Versioned的文件，可以根據需要恢復刪除或覆蓋的文件。
undelete supports the following options:
If the -l, -p, -s, -u and -v options are not specified, undelete recovers the specified files.
-l
print a listing of all versions of the specified file(s)
-p
purge (permanently delete) specified source file(s)
-s
turn the version attribute on for the specified directories and its subsequent child directories
-u
turn the version attribute off for the specified directories
-v
force the specified file(s) to be versioned
The following additional options are recognized:
-d
normally, if the specified file is a directory, undelete will operate on the files contained in that directory. If this option is specified, undelete operates on the directory itself.
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NOTE: undelete does not work on directories that are mounted.
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-i
undelete will prompt for confirmation prior to recovering a file that will overwrite the current version of the file. A y answer means that the undeletion should proceed. Any other answer prevents undelete from undeleting the file.
-f
undelete will recover the file(s) without prompting even if it is overwriting over an existing current version of the file. This option overrides the -i option. Note that this is the default if the standard input is not a terminal.
-r
undelete will operate recursively on any directories in the argument list. Symbolic links that are encountered with this option will not be traversed.
-m [+-]days
undelete will only consider files that were deleted less than ( - ), greater than ( + ) or exactly (neither - nor + ) days ago.
