COBOL Manual for TNS and TNS/R Programs

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1391

Disk Input and Output

HP COBOL Manual for TNS and TNS/R Programs—522555-006

28-44

Purging the Contents of a File From an HP COBOL

Program

Unless the CLEARONPURGE flag is set for a file, purging the file does not obliterate

the data on the disk. If security is a major consideration, use one of these to set the

CLEARONPURGE flag:

•

The FUP SECURE command with the CLEARONPURGE option

•

The SETMODE routine

For more information about the FILE_PURGE_ and SETMODE routines, see the

Guardian Procedure Calls Reference Manual.

Purging the Contents of a File From an HP COBOL Program

It is sometimes convenient to purge the contents of a file but keep the file in the

directory for later use. The HP COBOL run-time routines do this when you open a file

for output (if you have read access to the file). You might choose (for security) to purge

the contents of a temporary work file when you have finished working with it, because

merely purging the file does not erase the data from the disk.

The HP COBOL library routine COBOL_CONTROL_ is a multipurpose routine that

calls the operating system routine CONTROL, and whose function is determined by an

operation code. The operation code 20 enables a process to purge only the contents of

a file if the process has write access to the file. The process can even purge the data

from a temporary file whose name was assigned by Enscribe because you specified

only a volume name or assigned it to #TEMP.

The COBOL_CONTROL_ routine call for purging data requires two parameters. The

first parameter is the file-name described in the SELECT clause of the file-control

entry for the file; the second is the number 20 (which causes the file system to purge

the data in the file). Example:

ENTER "COBOL_CONTROL_" USING MYFILE 20

For more information about the CONTROL routine, see the Guardian Procedure Calls

Reference Manual.

Renaming a File From an HP COBOL Program

The FILE_RENAME_ procedure enables a process to rename a closed disk file,

provided the process has purge access to the file. If the file is a temporary file, the

process can call FILE_RENAME_ to make the file a permanent file. For more

information about the RENAME or FILE_RENAME_ routine, see the Guardian

Procedure Calls Reference Manual.