lofiadm(1M) System Administration Commands lofiadm(1M)NAMElofiadm - 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]
DESCRIPTIONlofiadm 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 con‐
tains 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 utili‐
ties 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 associa‐
tion, or print information about the current associations.
The lofi(7D) driver is not available and will not work inside a zone.
OPTIONS
The following options are supported:
-a file [device]
Add 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 spec‐
ify a device is provided for use in scripts that wish to re-estab‐
lish a particular set of associations.
-d file | device
Remove 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. File‐
names 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 fol‐
lowing 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 con‐
fidence.
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 help‐
ful 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 plat‐
form:
# 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 ALSOfsck(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 appropri‐
ate 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 anything. 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 com‐
patibility 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 8 May 2008 lofiadm(1M)
