TOPS-20 Commands Reference Manual

CLOSE

Closes open files in your job and releases their JFNs.

Format

@CLOSE (JFN) n

where:

n is the JFN (Job File Number) of a file.

Default n - all JFNs for open and closed files

Output

When the CLOSE command is completed, the system prints a message on your terminal for each JFN that it has closed or attempted to close.

Characteristics

CLOSE Usually Unnecessary

The CLOSE command is used to preserve the contents of a file after the abnormal termination of the program that opened it. Under ordinary conditions you do not need to use the CLOSE command.

Special Cases

CLOSE For Closed Files

If you give the CLOSE command for an existing but closed JFN, the JFN is released.

Restrictions

Closing Mapped Files

You cannot close files that are mapped into memory; in this case you may give the RESET command, which clears memory. (Note, however, that RESET will delete and expunge a mapped file if the file is new, rather than save it as CLOSE would. To save a new mapped file, give the SET PAGE-ACCESS 0:777 NONEXISTENT command, and follow this with CLOSE.) If RESET by itself does not close the file, you may first have to give the POP command to return to a higher level of the TOPS-20 command processor; then give the RESET command.

Once memory has been cleared, all files are closed for processes at the current and lower levels of TOPS-20.

Related Commands

INFORMATION FILE-STATUS for determining which files are open in your job
INFORMATION MEMORY-USAGE for determining which files are mapped
RESET for closing mapped files and clearing memory
SET PAGE NONEXISTENT for removing specified pages from memory

Examples

  1. Close an open file. 
    @CLOSE 4
 4  EDIT-BUFFER.OUT.100036   [OK]
  2. Try to close all your open files. Give the RESET command to close those that are mapped. (Note that the file EXEC.EXE, containing the TOPS-20 command processor, cannot be closed.) 
    @CLOSE
 3  TEST1.CBL.1   [OK]
 2  PS:<TEST>EDIT.EXE.4  Can't close file - File still mapped
 1  PS:<SYSTEM>EXEC.EXE.3  Can't close file - File still mapped
@RESET
@CLOSE
 1  PS:<SYSTEM>EXEC.EXE.3  Can't close file - File still mapped