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- OAPPEND
- Specifies that MVS™ sets the file offset to the end
of the file before each write, so that data is written at the end
of the file.
- OCREAT
- Specifies that:
- If the file does not exist, the system is to create it. If a directory
specified in the pathname does not exist, one is not created, and
the new file is not created.
- If the file already exists and OEXCL was not specified,
the system allows the program to use the existing file.
- If the file already exists and OEXCL was specified, the system
fails the allocation and the job step.
- OEXCL
- Specifies that:
- If the file does not exist, the system is to create it.
- If the file already exists, the system fails the allocation and
the job step.
The system ignores OEXCL if OCREAT is not also specified.
- ONOCTTY
- Specifies that if the PATH parameter identifies a terminal device,
opening of the file does not make the terminal device the controlling
terminal for the process.
- ONONBLOCK
- Specifies the following, depending on the type of file:
- For a FIFO special file:
- With ONONBLOCK specified and ORDONLY access: An open() function
for reading-only returns without delay.
- With ONONBLOCK not specified and ORDONLY
access: An open() function for reading-only blocks (waits)
until a process opens the file for writing.
- With ONONBLOCK specified and OWRONLY access: An open() function
for writing-only returns an error if no process currently has the
file open for reading.
- With ONONBLOCK not specified and OWRONLY
access: An open() function for writing-only blocks (waits)
until a process opens the file for reading.
- For a character special file that supports nonblocking open:
- If ONONBLOCK is specified: An open() function returns
without blocking (waiting) until the device is ready or available.
Device response depends on the type of device.
- If ONONBLOCK is not specified: An open() function
blocks (waits) until the device is ready or available.
Specification of ONONBLOCK has no effect on other file types.
- OSYNC
- Specifies that the system is to move data from buffer storage
to permanent storage before returning control from a callable service
that performs a write.
- OTRUNC
- Specifies that the system is to truncate the file length to
zero if all the following are true:
- The file specified on the PATH parameter exists.
- The file is a regular file.
- The file successfully opened with ORDWR or OWRONLY.
The system does not change the mode and owner. OTRUNC has
no effect on FIFO special files or character special files.
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