Difference between statvfs() and statfs() system calls?
Why do the statfs()
and 开发者_运维知识库statvfs()
calls both exist when they're so similar?
Under what circumstances would I prefer one over the other?
Err, "historical reasons".
Originally 4.4BSD defined a statfs()
call. Linux later implemented a slightly different call with the same name. Posix standardized it between all freenix and Unix versions by defining statvfs()
.
statfs()
is OS-specific
statvfs()
is posix-conforming
As they all return slightly different structures, later ones to come along can't replace the first.
In general you should use statvfs()
, the Posix one. Be careful about "use Posix" advice, though, as in some cases (pty, for example) the BSD (or whatever) one is more portable in practice.
If you just want file system capacity and usage information, the other answers are correct: prefer statvfs
because it is standard POSIX and handles large file sizes better. statfs
is BSD- and Linux-specific, with different structures on each. (Linux 2.6 added new statfs64
and fstatfs64
system calls that use an expanded structure to handle larger sizes.) However, statfs
is still useful on Linux for determining the file system type (assuming you're okay with writing Linux-specific code).
statfs()
is deprecated in favor of statvfs()
, which deals considerably better with large file support. statfs()
is known to do odd things for sizes that exceed the value of an unsigned long.
As far as I can tell (and remember), statvfs()
has been around since Redhat 7.3, just after being introduced as a POSIX replacement. You'll likely find it on (most) modern systems.
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