HP OpenVMS DCL Dictionary

F$UNIQUE (Alpha/I64 Only)

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

A character string containing the unique string.

Arguments

None.

Examples

#1
$ 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.

#2
$ 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 $

$ 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.

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