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Full Discussion: Access a File as a Device?
Top Forums UNIX for Advanced & Expert Users Access a File as a Device? Post 302609733 by Corona688 on Tuesday 20th of March 2012 11:15:16 AM
Old 03-20-2012
Here's an example using an old disk image I happened to have around:

Code:
$ /sbin/fdisk -ul gorgon-aug-7.img
You must set cylinders.
You can do this from the extra functions menu.

Disk gorgon-aug-7.img: 0 MB, 0 bytes
16 heads, 63 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

           Device Boot      Start         End      Blocks   Id  System
gorgon-aug-7.img1   *          63       98783       49360+  83  Linux
gorgon-aug-7.img2           98784     1099727      500472   82  Linux swap / Solaris
Partition 2 has different physical/logical endings:
     phys=(1023, 15, 63) logical=(1090, 15, 63)
gorgon-aug-7.img3        14772240    39102335    12165048    5  Extended
Partition 3 has different physical/logical beginnings (non-Linux?):
     phys=(1023, 15, 63) logical=(14655, 0, 1)
Partition 3 has different physical/logical endings:
     phys=(1023, 15, 63) logical=(38791, 15, 63)
gorgon-aug-7.img4         1099728    14772239     6836256   83  Linux
Partition 4 has different physical/logical beginnings (non-Linux?):
     phys=(1023, 15, 63) logical=(1091, 0, 1)
Partition 4 has different physical/logical endings:
     phys=(1023, 15, 63) logical=(14654, 15, 63)
gorgon-aug-7.img5        14772303    16237871      732784+  83  Linux
gorgon-aug-7.img6        16237935    39102335    11432200+  83  Linux

Partition table entries are not in disk order

# Partition 1 starts at 63.  In bytes that's 63*512 = 32256 bytes.
# Partition 1 ends at 98783, so is 98783-63 long, i.e. 50544640 bytes.
$ sudo mount -o loop,offset=32256,sizelimit=50544640 gorgon-aug-7.img mnt
$ ls mnt
System.map-2.6.34-gentoo-r1  grub        vmlinuz-2.6.34-gentoo-r1
boot                         lost+found
config-2.6.34-gentoo-r1      memtest86
$

This User Gave Thanks to Corona688 For This Post:
 

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prtvtoc(1M)						  System Administration Commands					       prtvtoc(1M)

NAME
prtvtoc - report information about a disk geometry and partitioning SYNOPSIS
prtvtoc [-fhs] [-t vfstab] [-m mnttab] device DESCRIPTION
The prtvtoc command allows the contents of the label to be viewed. The command can be used only by the super-user. The device name can be the file name of a raw device in the form of /dev/rdsk/c?t?d?s2 or can be the file name of a block device in the form of /dev/dsk/c?t?d?s2. OPTIONS
The following options are supported: -f Report on the disk free space, including the starting block address of the free space, number of blocks, and unused parti- tions. -h Omit the headers from the normal output. -m mnttab Use mnttab as the list of mounted filesystems, in place of /etc/mnttab. -s Omit all headers but the column header from the normal output. -t vfstab Use vfstab as the list of filesystem defaults, in place of /etc/vfstab. EXAMPLES
Example 1: Using the prtvtoc Command The following example uses the prtvtoc command on a 424-megabyte hard disk: example# prtvtoc /dev/rdsk/c0t3d0s2 * /dev/rdsk/c0t3d0s2 partition map * * Dimension: * 512 bytes/sector * 80 sectors/track * 9 tracks/cylinder * 720 sectors/cylinder * 2500 cylinders * 1151 accessible cylinders * * Flags: * 1: unmountable * 10: read-only * * First Sector Last * Partition Tag Flags Sector Count Sector Mount Directory 0 2 00 0 76320 76319 / 1 3 01 76320 132480 208799 2 5 00 0 828720 828719 5 6 00 208800 131760 340559 /opt 6 4 00 340560 447120 787679 /usr 7 8 00 787680 41040 828719 /export/home example# The data in the Tag column above indicates the type of partition, as follows: Name Number UNASSIGNED 0x00 BOOT 0x01 ROOT 0x02 SWAP 0x03 USR 0x04 BACKUP 0x05 STAND 0x06 VAR 0x07 HOME 0x08 ALTSCTR 0x09 CACHE 0x0a RESERVED 0x0b The data in the Flags column above indicates how the partition is to be mounted, as follows: Name Number MOUNTABLE, READ AND WRITE 0x00 NOT MOUNTABLE 0x01 MOUNTABLE, READ ONLY 0x10 Example 2: Using the prtvtoc Command with the -f Option The following example uses the prtvtoc command with the -f option on a 424-megabyte hard disk: example# prtvtoc -f /dev/rdsk/c0t3d0s2 FREE_START=0 FREE_SIZE=0 FREE_COUNT=0 FREE_PART=34 Example 3: Using the prtvtoc Command on a Disk Over One Terabyte The following example uses uses the prtvtoc command on a disk over one terabyte:. example# prtvtoc /dev/rdsk/c1t1d0s2 * /dev/rdsk/c1t1d0s2 partition map * * Dimensions: * 512 bytes/sector * 3187630080 sectors * 3187630013 accessible sectors * * Flags: * 1: unmountable * 10: read-only * * First Sector Last * Partition Tag Flags Sector Count Sector Mount Directory 0 2 00 34 262144 262177 1 3 01 262178 262144 524321 6 4 00 524322 3187089340 3187613661 8 11 00 3187613662 16384 318763004 ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
devinfo(1M), fmthard(1M), format(1M), mount(1M), attributes(5) WARNINGS
The mount command does not check the "not mountable" bit. SunOS 5.10 25 Jul 2002 prtvtoc(1M)
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