The SdU (SMARTdata Utilities) file system supports
sequential, indexed, and relative files.
When you create
an SdU file using
OPEN OUTPUT
and
WRITE statements, multiple files are
created:
- The file attributes are stored in files that have suffix .DDMEA.
- The primary index is stored in a file whose name begins with
the character @, followed by the file name.
- The alternate indexes are stored in files whose names end
with suffix .@00, .@01, and so forth.
Because SdU files consist of multiple files that refer to one another internally,
do not attempt to copy, move, or rename them.
When you delete an SdU file (using the
rm command),
be sure to also delete all its component files,
some of which are hidden due to their having names that begin with a period (
.).
To list all the components of an SdU file named
Log123
in the current directory for example, use the following command:
ls -l *Log123* .*Log123*
The SdU file system conforms to Standard COBOL 85.
Restrictions:
- SdU files must not be accessed other than from COBOL or PL/I programs,
because the metadata for SdU files is stored separately from the files (as described above).
- The SdU file system is not safe for use with multiple threads.