File-Sharing Options (Tru64 Unix) - Compaq COBOL AAQ2G1FTK User Manual

3
4
5
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
Open mode:
Allowing:
UPDATE
ALL
UPDATE
READERS
UPDATE
NONE
INPUT
ALL
INPUT
READERS
INPUT
NONE
UPDATE
INPUT
OUTPUT
ALL
READERS
NONE
G
1
2
3
4
5
Second stream is denied access to the file because the first stream intends
to write, while the second stream specifies read-only sharing.
Second stream is denied access to the file because the second stream
intends to write, while the first stream specifies read-only sharing.
No sharing; second will create new file version with OPEN OUTPUT.
UPDATE UPDATE
ALL READERS
G 5
6 3,4
1 1,3
G G
7 7
1 1
OPEN EXTEND or OPEN I-O
OPEN INPUT
OPEN OUTPUT
ALLOWING ALL or ALLOWING UPDATERS or ALLOWING WRITERS
ALLOWING READERS
ALLOWING NO OTHERS
Second stream successfully opens and file sharing is granted.
Second stream is denied access to the file because the first stream requires
exclusive access (the first stream specified NO OTHERS).
Second stream is denied access to the file because the second stream
requires exclusive access (the second stream specified NO OTHERS).
Second stream is denied access to the file because the first stream intends
to write, while the second stream specifies read-only sharing.
Second stream is denied access to the file because the second stream
intends to write, while the first stream specifies read-only sharing.
No sharing; second will create new file version with OPEN OUTPUT.
Sharing Files and Locking Records
8.3 Ensuring Successful File Sharing
Legend
SUBSEQUENT STREAM
UPDATE INPUT INPUT
NONE ALL READERS
2 G 5
2 G 5
1,2 1 1,3
2 G G
2 G G
1,2 1 1
Legend
Sharing Files and Locking Records 8–11
INPUT
NONE
2
2
1,2
2
2
1,2