Visit Our UNIX and Linux User Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #279
Difficulty: Easy
A microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system (OS). These mechanisms include low-level address space management, thread management, and inter-process communication (IPC).
True or False?
Linux & Unix Commands - Search Man Pages

statfs(2) [bsd man page]

STATFS(2)							System Calls Manual							 STATFS(2)

NAME
statfs, fstatfs - get file system statistics SYNOPSIS
#include <sys/param.h> #include <sys/mount.h> int statfs(path,buf) char *path; struct statfs *buf; int fstatfs(fd,buf) int fd; struct statfs *buf; DESCRIPTION
Statfs() returns information about a mounted file system. Path is the path name of any file within the mounted filesystem. Buf is a pointer to a statfs structure defined as follows: #define MNAMELEN 90 /* length of buffer for returned name */ struct statfs { short f_type; /* type of filesystem (see below) */ short f_flags; /* copy of mount flags */ short f_bsize; /* fundamental file system block size */ short f_iosize; /* optimal transfer block size */ long f_blocks; /* total data blocks in file system */ long f_bfree; /* free blocks in fs */ long f_bavail; /* free blocks avail to non-superuser */ ino_t f_files; /* total file nodes in file system */ ino_t f_ffree; /* free file nodes in fs */ u_long f_fsid[2]; /* file system id */ long f_spare[4]; /* spare for later */ char f_mntonname[MNAMELEN]; /* mount point */ char f_mntfromname[MNAMELEN]; /* mounted filesystem */ }; /* * File system types. - Only UFS is supported so the other types are not * given. */ #define MOUNT_UFS 1 /* Fast Filesystem */ Fields that are undefined for a particular file system are set to -1. Fstatfs() returns the same information about an open file referenced by descriptor fd. RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error. ERRORS
Statfs() fails if one or more of the following are true: [ENOTDIR] A component of the path prefix of Path is not a directory. [EINVAL] path contains a character with the high-order bit set. [ENAMETOOLONG] The length of a component of path exceeds 63 characters, or the length of path exceeds 255 characters. [ENOENT] The file referred to by path does not exist. [EACCES] Search permission is denied for a component of the path prefix of path. [ELOOP] Too many symbolic links were encountered in translating path. [EFAULT] Buf or path points to an invalid address. [EIO] An I/O error occurred while reading from or writing to the file system. Fstatfs() fails if one or more of the following are true: [EBADF] Fd is not a valid open file descriptor. [EFAULT] Buf points to an invalid address. [EIO] An I/O error occurred while reading from or writing to the file system. HISTORY
The statfs function first appeared in 4.4BSD. 4.4 Berkeley Distribution December 26, 1995 STATFS(2)

Check Out this Related Man Page

STATFS(2)						      BSD System Calls Manual							 STATFS(2)

NAME
statfs, statfs64, fstatfs, fstatfs64 -- get file system statistics SYNOPSIS
#include <sys/param.h> #include <sys/mount.h> int statfs(const char *path, struct statfs *buf); int fstatfs(int fd, struct statfs *buf); TRANSITIONAL SYNOPSIS (NOW DEPRECATED) int statfs64(const char *path, struct statfs64 *buf); int fstatfs64(int fd, struct statfs64 *buf); DESCRIPTION
The statfs() routine returns information about a mounted file system. The path argument is the path name of any file or directory within the mounted file system. The buf argument is a pointer to a statfs structure. When the macro _DARWIN_FEATURE_64_BIT_INODE is not defined (see stat(2) for more information on this macro), the statfs structure is defined as: typedef struct { int32_t val[2]; } fsid_t; #define MFSNAMELEN 15 /* length of fs type name, not inc. nul */ #define MNAMELEN 90 /* length of buffer for returned name */ struct statfs { /* when _DARWIN_FEATURE_64_BIT_INODE is NOT defined */ short f_otype; /* type of file system (reserved: zero) */ short f_oflags; /* copy of mount flags (reserved: zero) */ long f_bsize; /* fundamental file system block size */ long f_iosize; /* optimal transfer block size */ long f_blocks; /* total data blocks in file system */ long f_bfree; /* free blocks in fs */ long f_bavail; /* free blocks avail to non-superuser */ long f_files; /* total file nodes in file system */ long f_ffree; /* free file nodes in fs */ fsid_t f_fsid; /* file system id */ uid_t f_owner; /* user that mounted the file system */ short f_reserved1; /* reserved for future use */ short f_type; /* type of file system (reserved) */ long f_flags; /* copy of mount flags (reserved) */ long f_reserved2[2]; /* reserved for future use */ char f_fstypename[MFSNAMELEN]; /* fs type name */ char f_mntonname[MNAMELEN]; /* directory on which mounted */ char f_mntfromname[MNAMELEN]; /* mounted file system */ char f_reserved3; /* reserved for future use */ long f_reserved4[4]; /* reserved for future use */ }; However, when the macro _DARWIN_FEATURE_64_BIT_INODE is defined, the statfs structure is defined as: #define MFSTYPENAMELEN 16 /* length of fs type name including null */ #define MAXPATHLEN 1024 #define MNAMELEN MAXPATHLEN struct statfs { /* when _DARWIN_FEATURE_64_BIT_INODE is defined */ uint32_t f_bsize; /* fundamental file system block size */ int32_t f_iosize; /* optimal transfer block size */ uint64_t f_blocks; /* total data blocks in file system */ uint64_t f_bfree; /* free blocks in fs */ uint64_t f_bavail; /* free blocks avail to non-superuser */ uint64_t f_files; /* total file nodes in file system */ uint64_t f_ffree; /* free file nodes in fs */ fsid_t f_fsid; /* file system id */ uid_t f_owner; /* user that mounted the filesystem */ uint32_t f_type; /* type of filesystem */ uint32_t f_flags; /* copy of mount exported flags */ uint32_t f_fssubtype; /* fs sub-type (flavor) */ char f_fstypename[MFSTYPENAMELEN]; /* fs type name */ char f_mntonname[MAXPATHLEN]; /* directory on which mounted */ char f_mntfromname[MAXPATHLEN]; /* mounted filesystem */ uint32_t f_reserved[8]; /* For future use */ }; Note that the f_fstypename, f_mntonname, and f_mntfromname fields are also wider in this variant. Fields that are undefined for a particular file system are set to -1. The fstatfs() routine returns the same information about an open file referenced by descriptor fd. FLAGS
These are some of the flags that may be present in the f_flags field. MNT_RDONLY A read-only filesystem MNT_SYNCHRONOUS File system is written to synchronously MNT_NOEXEC Can't exec from filesystem MNT_NOSUID Setuid bits are not honored on this filesystem MNT_NODEV Don't interpret special files MNT_UNION Union with underlying filesysten MNT_ASYNC File system written to asynchronously MNT_EXPORTED File system is exported MNT_LOCAL File system is stored locally MNT_QUOTA Quotas are enabled on this file system MNT_ROOTFS This file system is the root of the file system MNT_DOVOLFS File system supports volfs MNT_DONTBROWSE File system is not appropriate path to user data MNT_UNKNOWNPERMISSIONS VFS will ignore ownership information on filesystem objects MNT_AUTOMOUNTED File system was mounted by automounter MNT_JOURNALED File system is journaled MNT_DEFWRITE File system should defer writes MNT_MULTILABEL MAC support for individual labels MNT_CPROTECT File system supports per-file encrypted data protection CAVEATS
In Mac OS X versions before 10.4, f_iosize is 4096. On these older systems, use MAXBSIZE instead. RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error. ERRORS
The statfs() routine fails if one or more of the following are true: [ENOTDIR] A component of the path prefix of Path is not a directory. [ENAMETOOLONG] The length of a component of path exceeds {NAME_MAX} characters, or the length of path exceeds {PATH_MAX} characters. [ENOENT] The file or directory referred to by path does not exist. [EACCES] Search permission is denied for a component of the path prefix of path. [ELOOP] Too many symbolic links were encountered in translating path. [EFAULT] Buf or path points to an invalid address. [EIO] An I/O error occurred while reading from or writing to the file system. The fstatfs() routine fails if one or more of the following are true: [EBADF] fd is not a valid open file descriptor. [EFAULT] Buf points to an invalid address. [EIO] An I/O error occurred while reading from or writing to the file system. TRANSITIONAL DESCRIPTION (NOW DEPRECATED) The statfs64 and fstatfs64 routines are equivalent to their corresponding non-64-suffixed routine, when 64-bit inodes are in effect. They were added before there was support for the symbol variants, and so are now deprecated. Instead of using these, set the _DARWIN_USE_64_BIT_INODE macro before including header files to force 64-bit inode support. The statfs64 structure used by these deprecated routines is the same as the statfs structure when 64-bit inodes are in effect (see above). HISTORY
The statfs() function first appeared in 4.4BSD. The statfs64() and fstatfs64() first appeared in Max OS X 10.5 (Leopard) and are now depre- cated in favor of the corresponding symbol variants. BSD
August 14, 2008 BSD

Featured Tech Videos