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MOUNT(8) BSD System Manager's Manual MOUNT(8) NAME mount -- mount file systems SYNOPSIS mount [-adfpruvw] [-t ufs | external_type] mount [-dfpruvw] special | node mount [-dfpruvw] [-o options] [-t ufs | external_type] special node DESCRIPTION The mount utility calls the mount(2) system call to prepare and graft a special device or the remote node (rhost:path) on to the file system tree at the point node. If either special or node are not provided, the ap- propriate information is taken from the fstab(5) file. The system maintains a list of currently mounted file systems. If no ar- guments are given to mount, this list is printed. The options are as follows: -a All the filesystems described in fstab(5) are mounted. Excep- tions are those marked as "noauto", excluded by the -t flag (see below), or if they are already mounted (except the root filesys- tem which is always remounted to preserve traditional single user mode behavior). -d Causes everything to be done except for the actual system call. This option is useful in conjunction with the -v flag to deter- mine what the mount command is trying to do. -f Forces the revocation of write access when trying to downgrade a filesystem mount status from read-write to read-only. Also forces the R/W mount of an unclean filesystem (dangerous; use with caution). -o Options are specified with a -o flag followed by a comma sepa- rated string of options. In case of conflicting options being specified, the rightmost option takes effect. The following op- tions are available: async All I/O to the file system should be done asynchronously. This is a dangerous flag to set, and should not be used unless you are prepared to recreate the file system should your system crash. current When used with the -u flag, this is the same as specify- ing the options currently in effect for the mounted filesystem. force The same as -f; forces the revocation of write access when trying to downgrade a filesystem mount status from read-write to read-only. Also forces the R/W mount of an unclean filesystem (dangerous; use with caution). fstab When used with the -u flag, this is the same as specify- ing all the options listed in the fstab(5) file for the filesystem. noasync Metadata I/O should be done synchronously, while data I/O should be done asynchronously. This is the default. noatime Do not update the file access time when reading from a file. This option is useful on filesystems where there are large numbers of files and performance is more criti- cal than updating the file access time (which is rarely ever important). This option is currently only supported on local filesystems. noauto This filesystem should be skipped when mount is run with the -a flag. noclusterr Disable read clustering. noclusterw Disable write clustering. nodev Do not interpret character or block special devices on the file system. This option is useful for a server that has file systems containing special devices for architec- tures other than its own. This option is set automati- cally when the user does not have super-user privileges. noexec Do not allow execution of any binaries on the mounted file system. This option is useful for a server that has file systems containing binaries for architectures other than its own. nosuid Do not allow set-user-identifier or set-group-identifier bits to take effect. Note: this option is worthless if a public available suid or sgid wrapper like suidperl(1) is installed on your system. It is set automatically when the user does not have super-user privileges. nosymfollow Do not follow symlinks on the mounted file system. rdonly The same as -r; mount the file system read-only (even the super-user may not write it). sync All I/O to the file system should be done synchronously. suiddir A directory on the mounted filesystem will respond to the SUID bit being set, by setting the owner of any new files to be the same as the owner of the directory. New direc- tories will inherit the bit from their parents. Execute bits are removed from the file, and it will not be given to root. This feature is designed for use on fileservers serving PC users via ftp, SAMBA, or netatalk. It provides secu- rity holes for shell users and as such should not be used on shell machines, especially on home directories. This option requires the SUIDDIR option in the kernel to work. Only UFS filesystems support this option. See chmod(2) for more information. update The same as -u; indicate that the status of an already mounted file system should be changed. union Causes the namespace at the mount point to appear as the union of the mounted filesystem root and the existing di- rectory. Lookups will be done in the mounted filesystem first. If those operations fail due to a non-existent file the underlying directory is then accessed. All cre- ates are done in the mounted filesystem. Any additional options specific to a filesystem type that is not one of the internally known types (see the -t option) may be passed as a comma separated list; these options are distinguished by a leading "-" (dash). Options that take a value are specified using the syntax -option=value. For example, the mount command: mount -t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp causes mount to execute the equivalent of: /sbin/mount_mfs -o nosuid -N -s 4000 /dev/dk0b /tmp Additional options specific to filesystem types which are not in- ternally known (see the description of the -t option below) may be described in the manual pages for the associated /sbin/mount_XXX utilities. -p Print mount information in fstab(5) format. Implies also the -v option. -r The file system is to be mounted read-only. Mount the file sys- tem read-only (even the super-user may not write it). The same as the rdonly argument to the -o option. -t ufs | external_type The argument following the -t is used to indicate the file system type. The type ufs is the default. The -t option can be used to indicate that the actions should only be taken on filesystems of the specified type. More than one type may be specified in a comma separated list. The list of filesystem types can be pre- fixed with "no" to specify the filesystem types for which action should not be taken. For example, the mount command: mount -a -t nonfs,mfs mounts all filesystems except those of type NFS and MFS. If the type is not one of the internally known types, mount will attempt to execute a program in /sbin/mount_XXX where XXX is re- placed by the type name. For example, nfs filesystems are mounted by the program /sbin/mount_nfs. Most filesystems will be dynamically loaded by their mount pro- grams if not already present in the kernel, using the vfsload(3) subroutine. Because this mechanism requires writable temporary space, the filesystem type containing /tmp must be compiled into the kernel, and the filesystems containing /tmp and /usr/bin/ld must be listed in /etc/fstab before any filesystems which might be dynamically loaded. -u The -u flag indicates that the status of an already mounted file system should be changed. Any of the options discussed above (the -o option) may be changed; also a file system can be changed from read-only to read-write or vice versa. An attempt to change from read-write to read-only will fail if any files on the filesystem are currently open for writing unless the -f flag is also specified. The set of options is determined by applying the options specified in the argument to -o and finally applying the -r or -w option. -v Verbose mode. -w The file system object is to be read and write. DIAGNOSTICS Various, most of them are self-explanatory. XXXXX filesystem is not available The kernel does not support the respective filesystem type. Note that support for a particular filesystem might be provided either on a static (kernel compile-time), or dynamic basis (loaded as a kernel module by kldload(8)). Normally, mount or its subprocesses attempt to dynamically load a filesystem module if it has not been configured statically, using vfsload(3). In this case, the above error message can also mean that you did not have permission to load the module. FILES /etc/fstab file system table SEE ALSO mount(2), vfsload(3), fstab(5), kldload(8), mount_cd9660(8), mount_ext2fs(8), mount_fdesc(8), mount_linprocfs(8), mount_mfs(8), mount_msdos(8), mount_nfs(8), mount_ntfs(8), mount_null(8), mount_nwfs(8), mount_portal(8), mount_procfs(8), mount_smbfs(8), mount_std(8), mount_umap(8), mount_union(8), sysctl(8), umount(8) BUGS It is possible for a corrupted file system to cause a crash. CAVEATS After a successful mount, the permissions on the original mount point de- termine if .. is accessible from the mounted file system. The minimum permissions for the mount point for traversal across the mount point in both directions to be possible for all users is 0111 (execute for all). HISTORY A mount utility appeared in Version 1 AT&T UNIX. BSD June 16, 1994 BSD
NAME | SYNOPSIS | DESCRIPTION | DIAGNOSTICS | FILES | SEE ALSO | BUGS | CAVEATS | HISTORY
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