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.\"	@(#)getvfsstat.2	8.3 (Berkeley) 5/25/95
.\"
.Dd March 27, 2021
.Dt GETVFSSTAT 2
.Os
.Sh NAME
.Nm getvfsstat
.Nd get list of all mounted file systems
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/types.h
.In sys/statvfs.h
.Ft int
.Fn getvfsstat "struct statvfs *buf" "size_t bufsize" "int flags"
.Sh DESCRIPTION
.Fn getvfsstat
returns information about all mounted file systems.
.Fa buf
is a pointer to an array of
.Nm statvfs
structures defined in
.Xr statvfs 5 .
.Pp
The buffer is filled with an array of
.Fa statvfs
structures, one for each mounted file system
up to the size specified by
.Fa bufsize .
.Pp
If
.Fa buf
is given as
.Dv NULL ,
.Fn getvfsstat
returns just the number of mounted file systems.
.Pp
Normally
.Fa flags
should be specified as
.Dv ST_WAIT .
If
.Fa flags
is set to
.Dv ST_NOWAIT ,
.Fn getvfsstat
will return the information it has available without requesting
an update from each file system.
Thus, some of the information will be out of date, but
.Fn getvfsstat
will not block waiting for information from a file system that is
unable to respond.
.Pp
Note that
.Fa bufsize
is the size of the buffer in bytes, not the count of structures that
will fit in it, and the return value is the count of structures, not
the size.
.Sh RETURN VALUES
Upon successful completion, the number of
.Fa statvfs
structures is returned.
Otherwise, \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn getvfsstat
fails if one or more of the following are true:
.Bl -tag -width Er
.It Bq Er EFAULT
.Fa buf
points to an invalid address.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Sh SEE ALSO
.Xr statvfs 2 ,
.Xr getmntinfo 3 ,
.Xr fstab 5 ,
.Xr mount 8
.Sh HISTORY
The
.Fn getvfsstat
function first appeared in
.Nx 3.0
to replace
.Fn getfsstat
which appeared in
.Bx 4.4 .