HP OpenVMS Systems Documentation

HP OpenVMS DCL Dictionary

Generates a string that is suitable to be a file name and is guaranteed to be unique across the cluster. Unique file names can be useful when creating temporary files. (See CLOSE/DISPOSITION for an example.)

The F$UNIQUE function has no arguments, but must be followed by a blank pair of parentheses.

Format

F$UNIQUE()

Return Value

Arguments

None.

Examples

$ WRITE SYS$OUTPUT F$UNIQUE()
414853555241159711D7DF797CCF573F
$
$ WRITE SYS$OUTPUT F$UNIQUE()
414853555241509811D7DF797E3F2777
$
      

This example shows how a unique string is returned on subsequent WRITE commands.

$ OPEN/WRITE TEMP_FILE 'F$UNIQUE()
$ DIRECTORY
Directory WORK1:[TEST]
594B53554C421C9C11D75463D61F58B7.DAT;1
Total of 1 file.
$
$ CLOSE/DISPOSITION=DELETE TEMP_FILE
$ DIRECTORY
%DIRECT-W-NOFILES, no files found
$
      

The first command creates a temporary file and gives it a unique name, which is displayed by the subsequent DIRECTORY command. After the file is later closed and deleted, it no longer shows up in the directory.