CompTIA Linux+ 3.8 Mounting and Unmounting Filesystems

-o

Additional Options for mount command

conv=code Most filesystems used on Microsoft and Apple OSs: msdos, umsdos, vfat, hpfs, and hfs

If code is b or binary, Linux doesn't modify the files' contents. If code is t or text, Linux auto-converts files between Linux-style and Windows- or Macintosh-style end-of-line characters. If code is a or auto, Linux applies the conversion unless the file is a known binary file format. It's usually best to leave this at its default value of binary because file conversions can cause serious problems for some applications and file types.

uid=value Most filesystems that don't support Unix-style permissions, such as vfat, hpfs, ntfs, and hfs

Sets the owner of all files. For instance, uid=1000 sets the owner to whomever has Linux user ID 1000. (Check Linux user IDs in the /etc/passwd file.)

umask=value Most filesystems that don't support Unix-style permissions, such as vfat, hpfs, ntfs, and hfs

Sets the umask for the permissions on files. value is interpreted in binary as bits to be removed from permissions on files. For instance, umask=027 yields permissions of 750, or -rwxr-x---. Used in conjunction with uid=value and gid=value, this option lets you control who can access files on FAT, HPFS, and many other foreign filesystems.

dmask=value Most filesystems that don't support Unix-style permissions, such as vfat, hpfs, ntfs, and hfs

Similar to umask, but sets the umask for directories only, not for files.

fmask=value Most filesystems that don't support Unix-style permissions, such as vfat, hpfs, ntfs, and hfs

Similar to umask, but sets the umask for files only, not for directories.

users All

Similar to user, except that any user may unmount a filesystem once it's been mounted.

owner All

Similar to user, except that the user must own the device file. Some distributions, such as Red Hat, assign ownership of some device files (such as /dev/fd0 for the floppy disk) to the console user, so this can be a helpful option.

ro All

Specifies a read-only mount of the filesystem. This is the default for filesystems that include no write access and for some with particularly unreliable write support.

rw All read/write filesystems

Specifies a read/write mount of the filesystem. This is the default for most read/write filesystems.

gid=value Most filesystems that don't support Unix-style permissions, such as vfat, hpfs, ntfs, and hfs

Works like uid=value, but sets the group of all files on the filesystem. You can find group IDs in the /etc/group file.

-w

causes Linux to attempt to mount the filesystem for both read and write operations.

-r

causes Linux to mount the filesystem read-only, even if it's normally a read/write filesystem

-a

causes mount to mount all of the filesystems listed in the /etc/fstab file, which specifies the most-used partitions and devices.

-a

causes the system to attempt to unmount all of the partitions listed in /etc/mtab, the file that holds information about mounted filesystems.

-r

tells umount that if it can't unmount a filesystem, it should attempt to remount it in read-only mode.

user or nouser All

Allows or disallows ordinary users to mount the filesystem. The default is nouser, but user is often appropriate for removable media. Used in /etc/fstab. When included in this file, user allows users to type mount /mountpoint (where /mountpoint is the assigned mount point) to mount a disk. Only the user who mounted the filesystem may unmount it.

defaults All

Causes the default options for this filesystem to be used. It's used primarily in the /etc/fstab file to ensure that the file includes an options column.

loop All

Causes the loopback device for this mount to be used. Allows you to mount a file as if it were a disk partition. For instance, mount -t vfat -o loop image.img /mnt/image mounts the file image.img as if it were a disk.

remount All

Changes one or more mount options without explicitly unmounting a partition. To use this option, you issue a mount command on an already-mounted filesystem but with remount along with any options that you want to change. This feature can be used to enable or disable write access to a partition, for example.

nojoliet iso9660

Disables Joliet extensions for ISO-9660 CD-ROMs.

norock iso9660

Disables Rock Ridge extensions for ISO-9660 CD-ROMs.

-f

Force Unmount:

-L label or -U uuid

Mount by Label or UUID: Instead of the device name, you can use the ____ or ____ options to tell mount to mount the filesystem with the specified label or UUID, respectively.

auto or noauto All

Mounts or doesn't mount the filesystem at boot time or when root issues the mount -a command. The default is auto, but noauto is appropriate for removable media. Used in /etc/fstab.

mount umount mount [-alrsvw] [-t fstype] [-o options] [device] [mountpoint] umount [-afnrv] [-t fstype] [device | mountpoint]

mount a filesystem unmount a filesystem

-v

mount parameter - produces verbose output—the program provides comments on operations as they occur.

-t fstype

mount parameter - specify the filesystem type.