Compaq COBOL AAQ2G1FTK - Manual (Page 263)

Sharing Files and Locking Records
8.3 Ensuring Successful File Sharing
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3 Second stream is denied access to the file because the first stream intends
to write, while the second stream specifies read-only sharing.
4 Second stream is denied access to the file because the second stream
intends to write, while the first stream specifies read-only sharing.
5 No sharing; second will create new file version with OPEN OUTPUT.
On Tru64 UNIX, Table 8–2 shows the valid and invalid OPEN ALLOWING
combinations between first and subsequent access streams. The table assumes no
file protection violations on the first stream.
Table 8–2 File-Sharing Options (Tru64 UNIX)
FIRST STREAM SUBSEQUENT STREAM
Open mode:
Allowing: UPDATE
ALL UPDATE
READERS UPDATE
NONE INPUT
ALL INPUT
READERS INPUT
NONE
UPDATE
ALL G 5 2 G 5 2
UPDATE
READERS 6 3,4 2 G 5 2
UPDATE
NONE 1 1,3 1,2 1 1,3 1,2
INPUT
ALL G G 2 G G 2
INPUT
READERS 7 7 2 G G 2
INPUT
NONE 1 1 1,2 1 1 1,2
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UPDATE OPEN EXTEND or OPEN I-O
INPUT OPEN INPUT
OUTPUT OPEN OUTPUT
ALL ALLOWING ALL or ALLOWING UPDATERS or ALLOWING WRITERS
READERS ALLOWING READERS
NONE ALLOWING NO OTHERS
G Second stream successfully opens and file sharing is granted.
1 Second stream is denied access to the file because the first stream requires
exclusive access (the first stream specified NO OTHERS).
2 Second stream is denied access to the file because the second stream
requires exclusive access (the second stream specified NO OTHERS).
3 Second stream is denied access to the file because the first stream intends
to write, while the second stream specifies read-only sharing.
4 Second stream is denied access to the file because the second stream
intends to write, while the first stream specifies read-only sharing.
5 No sharing; second will create new file version with OPEN OUTPUT.
Sharing Files and Locking Records 8–11