TOPS-20 Commands Reference Manual

home PDP-10 TOPS-20 Commands Reference Manual Top: Chapter 2 Command description

FORK

Makes the specified fork your current fork. The current fork is the fork to which TOPS-20 commands are applied.

Format

@FORK (IS) fork

where:

fork is one of the following:

Fork name
Fork number
Default - the fork with the highest fork number

Characteristics

Default Fork

If you do not specify a fork name or number with the FORK command, the fork with the highest fork number (usually the last fork created) becomes your current fork, and the fork name is printed in brackets, [FORK-NAME].

Fork Name and Number

Forks are named after the program they contain and are numbered in the order that they are created. In multiforking class commands, the fork name and number are interchangeable.

Hints

More Information

The FORK command is one of the TOPS-20 multiforking-class commands. For more information about multiforking, see the section named, Running Multiple Programs, in the TOPS-20 User's Guide.

Special Cases

Fork 0

If you are a user with enabled WHEEL privileges you can give the command, FORK 0. This references the command processor (EXEC) itself.

Related Commands

INFORMATION MEMORY-USAGE	for examining memory of the current process
INFORMATION FORK-STATUS	for finding out the number and status of each fork in your job
INFORMATION PROGRAM-STATUS	for finding what fork attributes have been set with the SET PROGRAM command and the number and status of each fork in your job
CONTINUE, FREEZE, KEEP, RESET, SET NAME, SET PROGRAM, and UNKEEP	other multiforking-class commands

Examples

Make the first fork you created your current fork.
```
@FORK 1
```

Display the fork status, and make the last fork you created your current fork. Then, redisplay the fork status to check the result. (In the FORK-STATUS display, an arrow (=>) indicates the current fork).

@INFORMATION FORK-STATUS
 => EDIT (1): Kept, HALT at 6254, 0:00:12.8
    DUMPER (2): Kept, HALT at 6065, 0:00:30.1
    HOST (3): Kept, HALT at 67543, 0:00:09.3
@FORK
@INFORMATION FORK-STATUS
    EDIT (1): Kept, HALT at 6254, 0:00:12.8
    DUMPER (2): Kept, HALT at 6065, 0:00:30.1
 => HOST (3): Kept, HALT at 67543, 0:00:09.3

Make the FORK named DUMPER your current fork; then display the fork status.

@FORK DUMPER
@INFORMATION FORK-STATUS
    EDIT (1): Kept, HALT at 6254, 0:00:12.8
 => DUMPER (2): Kept, HALT at 6065, 0:00:30.1
    HOST (3): Kept, HALT at 67543, 0:00:09.3

Find out which forks exist in your job. Look at memory for the first fork, then examine a particular location. Make the second inferior fork current, and do the same thing there.

@INFORMATION FORK-STATUS
 => QUILL (1): Kept, HALT at 50340, 0:00:04.5
       Fork 2: HALT at 21010, 0:00:00.4
@INFORMATION MEMORY-USAGE

124. pages, Entry vector loc 4570 len 3

  Section 0     R, W, E,  Private
0-5      Private   R, W, E
6-55     RANDOM:<QUILL>TECPUR.EXE.1120  1-50    R, E
56-77    Private   R, W, E
116-123  Private   R, W, E
620-637  RANDOM:<QUILL>ABBRE.:EJ.614  0-17   R, E
640-643  RANDOM:<QUILL>TYPE.:EJ.27  0-3   R, E
644-645  RANDOM:<QUILL>INIT.:EJ.17  0-1   R, E
646-661  RANDOM:<QUILL>LSTSQ.:EJ.424  0-13   R, E
662-663  RANDOM:<QUILL>SYSTEM.:EJ.1  0-1   R, E
@EXAMINE 6400
6400/ 200040,,4636
@FORK 2
@INFORMATION MEMORY-USAGE

95. pages, Entry vector loc 15710 len 3

  Section 0     R, W, E,  Private
0-11     Private   R, W, E
13-15    Private   R, W, E
16-110   RANDOM:<TOOLS>DEFFNA.3  3-75   R, CW, E
117      Private   R, W, E
166      Private   R, W, E
170      Private   R, W, E
172      Private   R, W, E
174      Private   R, W, E
224      Private   R, W, E
226      Private   R, W, E
231-250  Private   R, W, E
@EXAMINE 2600
2600/ 0