lofiadm(1M)                                               System Administration Commands                                               lofiadm(1M)

NAME

       lofiadm - administer files available as block devices through lofi

SYNOPSIS

       /usr/sbin/lofiadm -a file [device]

       /usr/sbin/lofiadm -d  file | device

       /usr/sbin/lofiadm [ file | device]

DESCRIPTION

       lofiadm  administers lofi(7D), the loopback file driver. lofi(7D) allows a file to be associated with a block device. That file can then be
       accessed through the block device. This is useful when the file contains an image of some filesystem (such as a floppy  or  CD-ROM  image),
       because  the  block  device can then be used with the normal system utilities for mounting, checking or repairing filesystems. See fsck(1M)
       and mount(1M).

       Use lofiadm to add a file as a loopback device, remove such an association, or print information about the current associations.

OPTIONS

       The following options are supported:

       -a  file [deviceAdd file as a block device.

                       If device is not specified, an available device is picked.

                       If device is specified, lofiadm attempts to assign it to file. device must be available or lofiadm will fail.  The  ability
                       to specify a device is provided for use in scripts that wish to re-establish a particular set of associations.

       -d file | deviceRemove an association by file or device name, if the associated block device is not busy, and deallocates the block device.

OPERANDS

       The following operands are supported:

       file            Print the block device associated with file.

       device          Print the file name associated with the block device device.

                       Without arguments, print a list of the current associations. Filenames must be valid absolute pathnames.

                       When  a  file is added, it is opened for reading or writing by root. Any restrictions apply (such as restricted root access
                       over NFS). The file is held open until the association is removed. It is not actually accessed until the  block  device  is
                       used, so it will never be written to if the block device is only opened read-only.

EXAMPLES

       Example 1: Mounting an Existing CD-ROM Image

       You should ensure that Solaris understands the image before creating the CD. lofi allows you to mount the image and see if it works.

       This example mounts an existing CD-ROM image (sparc.iso), of the Red Hat 6.0 CD which was downloaded from the Internet. It was created with
       the mkisofs utility from the Internet.

       Use lofiadm to attach a block device to it:

       # lofiadm -a /home/mike_s/RH6.0/sparc.iso
       /dev/lofi/1

       lofiadm picks the device and prints the device name to the standard output. You can run lofiadm again by issuing the following command:

       # lofiadm
       Block Device     File
       /dev/lofi/1      /home/mike_s/RH6.0/sparc.iso

       Or, you can give it one name and ask for the other, by issuing the following command:

       # lofiadm /dev/lofi/1
       /home/mike_s/RH6.0/sparc.iso

       Use the mount command to mount the image:

       # mount -F hsfs -o ro /dev/lofi/1 /mnt

       Check to ensure that Solaris understands the image:

       # df -k /mnt
       Filesystem            kbytes    used   avail capacity  Mounted on
       /dev/lofi/1           512418  512418       0   100%    /mnt
       # ls /mnt
       ./            RedHat/       doc/          ls-lR         rr_moved/
       ../           TRANS.TBL     dosutils/     ls-lR.gz      sbin@
       .buildlog     bin@          etc@          misc/         tmp/
       COPYING       boot/         images/       mnt/          usr@
       README        boot.cat*     kernels/      modules/
       RPM-PGP-KEY   dev@          lib@          proc/

       Solaris can mount the CD-ROM image, and understand the filenames. The image was created properly, and you can now create  the  CD-ROM  with
       confidence.

       As a final step, unmount and detach the images:

       # umount /mnt
       # lofiadm -d /dev/lofi/1
       # lofiadm
       Block Device             File

       Example 2: Mounting a Floppy Image

       This is similar to Example 1.

       Using  lofi  to  help you mount files that contain floppy images is helpful if a floppy disk contains a file that you need, but the machine
       which you are on does not have a floppy drive. It is also helpful if you do not want to take the time to use the dd  command  to  copy  the
       image to a floppy.

       This is an example of getting to MDB floppy for Solaris on an x86 platform:

       # lofiadm -a /export/s28/MDB_s28x_wos/latest/boot.3
       /dev/lofi/1
       # mount -F pcfs /dev/lofi/1 /mnt
       # ls /mnt
       ./            COMMENT.BAT*  RC.D/         SOLARIS.MAP*
       ../           IDENT*        REPLACE.BAT*  X/
       APPEND.BAT*   MAKEDIR.BAT*  SOLARIS/
       # umount /mnt
       # lofiadm -d /export/s28/MDB_s28x_wos/latest/boot.3

       Example 3: Making a UFS Filesystem on a File

       Making a UFS filesystm on a file can be useful, particularly if a test suite requires a scratch filesystem. It can be painful (or annoying)
       to have to re-partition a disk just for the test suite, but you do not have to. You can newfs a file with lofi

       Create the file:

       # mkfile 35m /export/home/test

       Attach it to a block device. You also get the character device that newfs requires, so newfs that:

       # lofiadm -a /export/home/test
       /dev/lofi/1
       # newfs /dev/rlofi/1
       newfs: construct a new file system /dev/rlofi/1: (y/n)? y
       /dev/rlofi/1:   71638 sectors in 119 cylinders of 1 tracks, 602 sectors
               35.0MB in 8 cyl groups (16 c/g, 4.70MB/g, 2240 i/g)
       super-block backups (for fsck -F ufs -o b=#) at:
        32, 9664, 19296, 28928, 38560, 48192, 57824, 67456,

       Note that ufs might not be able to use the entire file. Mount and use the filesystem:

       # mount /dev/lofi/1 /mnt
       # df -k /mnt
       Filesystem            kbytes    used   avail capacity  Mounted on
       /dev/lofi/1            33455       9   30101     1%    /mnt
       # ls /mnt
       ./           ../          lost+found/
       # umount /mnt
       # lofiadm -d /dev/lofi/1

       Example 4: Creating a PC (FAT) File System on a Unix File

       The following series of commands creates a FAT file system on a Unix file. The file is associated with a block device created by lofiadm.

       # mkfile 10M /export/test/testfs
       # lofiadm -a /export/test testfs
       /dev/lofi/1
       Note use of rlofi, not lofi, in following command.
       # mkfs -F pcfs -o nofdisk,size=20480 /dev/rlofi/1
       Construct a new FAT file system on /dev/rlofi/1: (y/n)? y
       # mount -F pcfs /dev/lofi/1 /mnt
       # cd /mnt
       # df -k .
       Filesystem            kbytes    used   avail capacity  Mounted on
       /dev/lofi/1            10142       0   10142     0%    /mnt

ENVIRONMENT VARIABLES

       See environ(5) for descriptions of the following environment variables that affect the execution  of  lofiadm:  LC_CTYPE,  LC_MESSAGES  and
       NLSPATH.

EXIT STATUS

       The following exit values are returned:

       0               Successful completion.

       >0              An error occurred.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |ATTRIBUTE TYPE               |ATTRIBUTE VALUE              |
       +-----------------------------+-----------------------------+
       |Availability                 |SUNWcsu                      |
       +-----------------------------+-----------------------------+

SEE ALSO

       fsck(1M), mount(1M), mount_ufs(1M), newfs(1M), attributes(5), lofi(7D), lofs(7FS)

NOTES

       Just  as  you  would  not directly access a disk device that has mounted file systems, you should not access a file associated with a block
       device except through the lofi file driver. It might also be appropriate to ensure that the file has  appropriate  permissions  to  prevent
       such access.

       Associations are not persistant across reboots. A script can be used to re-establish them if required.

       The  abilities  of  lofiadm,  and who can use them, are controlled by the permissions of /dev/lofictl. Read-access allows query operations,
       such as listing all the associations. Write-access is required to do  any  state-changing  operations,  like  adding  an  association.   As
       shipped,  /dev/lofictl  is  owned  by root, in group sys, and mode 0644, so all users can do query operations but only root can change any-
       thing. The administrator can give users write-access, allowing them to add or delete associations, but that is very likely a security  hole
       and should probably only be given to a trusted group.

       When  mounting  a filesystem image, take care to use appropriate mount options. In particular, the nosuid mount option might be appropriate
       for UFS images whose origin is unknown. Also, some options might not be useful or appropriate, like logging or forcedirectio for  UFS.  For
       compatibility purposes, a raw device is also exported along with the block device. For example, newfs(1M) requires one.

       The output of lofiadm (without arguments) might change in future releases.

SunOS 5.10                                                          17 Nov 1999                                                        lofiadm(1M)