HP-UX Reference (11i v2 04/09) - 1M System Administration Commands A-M (vol 3)

f
fscat_vxfs(1M) fscat_vxfs(1M)
NAME
fscat_vxfs: fscat - cat a VxFS file system
SYNOPSIS
fscat [-F vxfs][-f
output-file][-o offset][-l length][
-b block_size ] special
DESCRIPTION
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 spe-
cial 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:
"512 b"
All numbers entered as options must be in multiples of 512 bytes. For example, a value of 5713 as an
offset is rejected.
Options
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 mega-
byte.
-F vxfs Specify the VxFS file system type.
-f output-file Specify an output file in which to write the datastream.
-l length Specify the transfer length, in bytes. A length of 0 includes the remainder of the file sys-
tem after the specified offset.
-o offset Specify the starting offset in bytes.
Operands
fscat recognizes the following operand:
special Name of the special device from which the VxFS file system is accessed.
Notes
Snapshot file systems are only available with the HP OnLineJFS product.
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 con-
tains 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 writ-
ten 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.
Section 1M−−218 Hewlett-Packard Company − 1 − HP-UX 11i Version 2: September 2004