What does “whether synchronized I/O can be used with the associated file” mean?
From Advanced Programming in the UNIX® Environment:
For
_PC_ASYNC_IO,_PC_PRIO_IO, and_PC_SYNC_IO, the referenced file
must not be a directory.
Name of option | Indicates ... |name argument
_POSIX_SYNC_IO |whether synchronized I/O can be used with |_PC_SYNC_IO
the associated file
So I assume the usage would belong return_value = pathconf("/a/path/filename",_PC_SYNC_IO).
It looks like it's a way to get a specific file's "setting".
Is this thing can be set to a file? How can I set it?
And what does synchronized I/O mean as to a file? I mean, I don't understand how synchronized I/O could be a setting of a file? Shouldn't it be a programming aspect thing instead of merely a "setting"?
files
edited Feb 21 at 15:36
Stephen Kitt
175k24400478
asked Feb 21 at 14:45
RickRick
24127
add a comment |
From Advanced Programming in the UNIX® Environment:
For
_PC_ASYNC_IO,_PC_PRIO_IO, and_PC_SYNC_IO, the referenced file
must not be a directory.
Name of option | Indicates ... |name argument
_POSIX_SYNC_IO |whether synchronized I/O can be used with |_PC_SYNC_IO
the associated file
So I assume the usage would belong return_value = pathconf("/a/path/filename",_PC_SYNC_IO).
It looks like it's a way to get a specific file's "setting".
Is this thing can be set to a file? How can I set it?
And what does synchronized I/O mean as to a file? I mean, I don't understand how synchronized I/O could be a setting of a file? Shouldn't it be a programming aspect thing instead of merely a "setting"?
files
edited Feb 21 at 15:36
Stephen Kitt
175k24400478
asked Feb 21 at 14:45
RickRick
24127
add a comment |
From Advanced Programming in the UNIX® Environment:
For
_PC_ASYNC_IO,_PC_PRIO_IO, and_PC_SYNC_IO, the referenced file
must not be a directory.
Name of option | Indicates ... |name argument
_POSIX_SYNC_IO |whether synchronized I/O can be used with |_PC_SYNC_IO
the associated file
So I assume the usage would belong return_value = pathconf("/a/path/filename",_PC_SYNC_IO).
It looks like it's a way to get a specific file's "setting".
Is this thing can be set to a file? How can I set it?
And what does synchronized I/O mean as to a file? I mean, I don't understand how synchronized I/O could be a setting of a file? Shouldn't it be a programming aspect thing instead of merely a "setting"?
files
edited Feb 21 at 15:36
Stephen Kitt
175k24400478
asked Feb 21 at 14:45
RickRick
24127
From Advanced Programming in the UNIX® Environment:
For
_PC_ASYNC_IO,_PC_PRIO_IO, and_PC_SYNC_IO, the referenced file
must not be a directory.
Name of option | Indicates ... |name argument
_POSIX_SYNC_IO |whether synchronized I/O can be used with |_PC_SYNC_IO
the associated file
So I assume the usage would belong return_value = pathconf("/a/path/filename",_PC_SYNC_IO).
It looks like it's a way to get a specific file's "setting".
Is this thing can be set to a file? How can I set it?
And what does synchronized I/O mean as to a file? I mean, I don't understand how synchronized I/O could be a setting of a file? Shouldn't it be a programming aspect thing instead of merely a "setting"?
files
files
edited Feb 21 at 15:36
Stephen Kitt
175k24400478
asked Feb 21 at 14:45
RickRick
24127
edited Feb 21 at 15:36
Stephen Kitt
175k24400478
asked Feb 21 at 14:45
RickRick
24127
edited Feb 21 at 15:36
Stephen Kitt
175k24400478
edited Feb 21 at 15:36
Stephen Kitt
175k24400478
edited Feb 21 at 15:36
Stephen Kitt
175k24400478
175k24400478
asked Feb 21 at 14:45
RickRick
24127
asked Feb 21 at 14:45
RickRick
24127
asked Feb 21 at 14:45
RickRick
24127
24127
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
The result of pathconf can vary depending on the file, for some of the arguments it can be given (_PC_NAME_MAX, _PC_ASYNC_IO, and a few others), but for most arguments the result is a platform-dependent constant. The values you retrieve using pathconf aren’t per-file settings, they’re properties of the system and the type of file; you can’t set them.
Synchronized I/O in this context refers to synchronous reads and writes from and to a file, as controlled by O_SYNC and related flags which can be specified on open calls. pathconf(..., _PC_SYNC_IO) will tell you whether those flags are supported (note that O_SYNC is always supposed to be supported on regular files anyway, regardless of the result of pathconf).
answered Feb 21 at 14:57
Stephen KittStephen Kitt
175k24400478
So no matter what file I put intopathconf("/no/matter/what/file",_PC_SYNC_IO), the result would be the same? That's ... Oh god, then why requires the first argument at all..?
– Rick
Feb 21 at 15:31
It’s a generic interface which supports a variety of settings, some of which are path-dependent (e.g. because they depend on the type of the file). You’re not really supposed to know ahead of time that any given setting is a constant ;-).
– Stephen Kitt
Feb 21 at 15:34
add a comment |
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1 Answer
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oldest
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
The result of pathconf can vary depending on the file, for some of the arguments it can be given (_PC_NAME_MAX, _PC_ASYNC_IO, and a few others), but for most arguments the result is a platform-dependent constant. The values you retrieve using pathconf aren’t per-file settings, they’re properties of the system and the type of file; you can’t set them.
Synchronized I/O in this context refers to synchronous reads and writes from and to a file, as controlled by O_SYNC and related flags which can be specified on open calls. pathconf(..., _PC_SYNC_IO) will tell you whether those flags are supported (note that O_SYNC is always supposed to be supported on regular files anyway, regardless of the result of pathconf).
answered Feb 21 at 14:57
Stephen KittStephen Kitt
175k24400478
So no matter what file I put intopathconf("/no/matter/what/file",_PC_SYNC_IO), the result would be the same? That's ... Oh god, then why requires the first argument at all..?
– Rick
Feb 21 at 15:31
It’s a generic interface which supports a variety of settings, some of which are path-dependent (e.g. because they depend on the type of the file). You’re not really supposed to know ahead of time that any given setting is a constant ;-).
– Stephen Kitt
Feb 21 at 15:34
add a comment |
The result of pathconf can vary depending on the file, for some of the arguments it can be given (_PC_NAME_MAX, _PC_ASYNC_IO, and a few others), but for most arguments the result is a platform-dependent constant. The values you retrieve using pathconf aren’t per-file settings, they’re properties of the system and the type of file; you can’t set them.
Synchronized I/O in this context refers to synchronous reads and writes from and to a file, as controlled by O_SYNC and related flags which can be specified on open calls. pathconf(..., _PC_SYNC_IO) will tell you whether those flags are supported (note that O_SYNC is always supposed to be supported on regular files anyway, regardless of the result of pathconf).
answered Feb 21 at 14:57
Stephen KittStephen Kitt
175k24400478
So no matter what file I put intopathconf("/no/matter/what/file",_PC_SYNC_IO), the result would be the same? That's ... Oh god, then why requires the first argument at all..?
– Rick
Feb 21 at 15:31
It’s a generic interface which supports a variety of settings, some of which are path-dependent (e.g. because they depend on the type of the file). You’re not really supposed to know ahead of time that any given setting is a constant ;-).
– Stephen Kitt
Feb 21 at 15:34
add a comment |
The result of pathconf can vary depending on the file, for some of the arguments it can be given (_PC_NAME_MAX, _PC_ASYNC_IO, and a few others), but for most arguments the result is a platform-dependent constant. The values you retrieve using pathconf aren’t per-file settings, they’re properties of the system and the type of file; you can’t set them.
Synchronized I/O in this context refers to synchronous reads and writes from and to a file, as controlled by O_SYNC and related flags which can be specified on open calls. pathconf(..., _PC_SYNC_IO) will tell you whether those flags are supported (note that O_SYNC is always supposed to be supported on regular files anyway, regardless of the result of pathconf).
answered Feb 21 at 14:57
Stephen KittStephen Kitt
175k24400478
The result of pathconf can vary depending on the file, for some of the arguments it can be given (_PC_NAME_MAX, _PC_ASYNC_IO, and a few others), but for most arguments the result is a platform-dependent constant. The values you retrieve using pathconf aren’t per-file settings, they’re properties of the system and the type of file; you can’t set them.
Synchronized I/O in this context refers to synchronous reads and writes from and to a file, as controlled by O_SYNC and related flags which can be specified on open calls. pathconf(..., _PC_SYNC_IO) will tell you whether those flags are supported (note that O_SYNC is always supposed to be supported on regular files anyway, regardless of the result of pathconf).
answered Feb 21 at 14:57
Stephen KittStephen Kitt
175k24400478
edited Feb 21 at 15:25
answered Feb 21 at 14:57
Stephen KittStephen Kitt
175k24400478
answered Feb 21 at 14:57
Stephen KittStephen Kitt
175k24400478
answered Feb 21 at 14:57
Stephen KittStephen Kitt
175k24400478
175k24400478
So no matter what file I put intopathconf("/no/matter/what/file",_PC_SYNC_IO), the result would be the same? That's ... Oh god, then why requires the first argument at all..?
– Rick
Feb 21 at 15:31
It’s a generic interface which supports a variety of settings, some of which are path-dependent (e.g. because they depend on the type of the file). You’re not really supposed to know ahead of time that any given setting is a constant ;-).
– Stephen Kitt
Feb 21 at 15:34
add a comment |
So no matter what file I put intopathconf("/no/matter/what/file",_PC_SYNC_IO), the result would be the same? That's ... Oh god, then why requires the first argument at all..?
– Rick
Feb 21 at 15:31
It’s a generic interface which supports a variety of settings, some of which are path-dependent (e.g. because they depend on the type of the file). You’re not really supposed to know ahead of time that any given setting is a constant ;-).
– Stephen Kitt
Feb 21 at 15:34
So no matter what file I put into
pathconf("/no/matter/what/file",_PC_SYNC_IO), the result would be the same? That's ... Oh god, then why requires the first argument at all..?– Rick
Feb 21 at 15:31
So no matter what file I put into
pathconf("/no/matter/what/file",_PC_SYNC_IO), the result would be the same? That's ... Oh god, then why requires the first argument at all..?– Rick
Feb 21 at 15:31
It’s a generic interface which supports a variety of settings, some of which are path-dependent (e.g. because they depend on the type of the file). You’re not really supposed to know ahead of time that any given setting is a constant ;-).
– Stephen Kitt
Feb 21 at 15:34
It’s a generic interface which supports a variety of settings, some of which are path-dependent (e.g. because they depend on the type of the file). You’re not really supposed to know ahead of time that any given setting is a constant ;-).
– Stephen Kitt
Feb 21 at 15:34
add a comment |
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