NAME [Toc] [Back]
fscat_vxfs: fscat - cat a VxFS file system
SYNOPSIS [Toc] [Back]
fscat [-F vxfs] [-f output-file] [-o offset] [-l length]
[-b block_size] special
DESCRIPTION [Toc] [Back]
fscat provides an interface to a VxFS snapshot file system, similar to
that provided by dd, invoked on the block or character special file of
regular VxFS file systems. fscat works when executed on the special
device of any VxFS file system.
On most VxFS file systems, the block or character special file for the
file system provides access to a raw image of the file system to back
up the file system to tape. On a snapshot file system, access to the
corresponding block or character special file provides little useful
information. fscat provides a stream of bytes representing the file
system snapshot. This datastream is written by default to standard
output, although the -f output-file option can be used to specify
another destination. The datastream on standard output can be
processed several ways, such as in a pipeline, or written to a tape.
By default, the output is a stream of bytes that starts at the
beginning of the file system and continues to the last byte. On a
snapshot file system, data is read from the file system using special
ioctls on the mount point. On other VxFS file systems, data is read
from the specified special file. Unless otherwise specified, data is
written to standard output.
All numbers entered as option arguments can have 0 as a prefix to
indicate octal, or 0x as a prefix to indicate hexadecimal. A b or B
can be appended to indicate the value is in 512-byte blocks, a k or K
to indicate the value is in kilobytes, an m or M to indicate the value
is in megabytes, or a g or G to indicate the value is in gigabytes.
An appended letter can be separated from the number by a space, in
which case the letter and number should be enclosed in a set of
quotes. For example:
All numbers entered as options must be in multiples of 512 bytes. For
example, a value of 5713 as an offset is rejected.
Options [Toc] [Back]
fscat recognizes the following options:
-b block_size Specify the output block size, in bytes. block_size
must be less than or equal to 1 megabyte.
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-F vxfs Specify the VxFS file system type.
-f output-file Specify an output file in which to write the
-l length Specify the transfer length, in bytes. A length of 0
includes the remainder of the file system after the
-o offset Specify the starting offset in bytes.
Operands [Toc] [Back]
fscat recognizes the following operand:
special Name of the special device from which the VxFS
file system is accessed.
Notes [Toc] [Back]
Snapshot file systems are only available with the HP OnLineJFS
A snapshot file system cannot be written to.
A snapshot file system exists only as long as it is mounted; once
unmounted, the special file no longer contains a snapshot file system.
When fscat is run on a mounted VxFS snapshot, the content of free
blocks (that is, blocks not allocated to any file or metadata) is
undefined. The content of free blocks can change after additional
data is written to the primary (snapped) file system, but blocks
associated with files always display the content they had when the
snapshot was created.
fscat does not work with Storage Checkpoints.
SEE ALSO [Toc] [Back]
dd(1), fs_vxfs(4), vxfsio(7).
Hewlett-Packard Company - 2 - HP-UX 11i Version 2: August 2003 [ Back ]