05-18-2006
Clearing file contents
Hi,
We need to clear the contents of a file. For this we tried using the commands like - '>filename' and 'cat filename > /dev/null'.
If the file size is large, the above commands will clear the file contents but the size of the file remains the same (checked using the command 'ls -l filename').
Are there any other UNIX commands which will empty the file contents?
Regards,
Raghavendra
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LEARN ABOUT OPENSOLARIS
sbdadm
sbdadm(1M) System Administration Commands sbdadm(1M)
NAME
sbdadm - SCSI Block Disk command line interface
SYNOPSIS
sbdadm create-lu [-s, --size size] filename
sbdadm delete-lu lu_name
sbdadm import-lu lu_name
sbdadm list-lu lu_name
sbdadm modify-lu [-s, --size size] lu_name | filename
DESCRIPTION
The sbdadm command creates and manages SCSI-block-device-based logical units that are registered with the SCSI Target Mode Framework
(STMF).
SUB-COMMANDS
The sbdadm command supports the subcommands listed below. Note that if you enter a question mark as an argument to the command (sbdadm ?),
sbdadm responds with a help display.
create-lu [-s, --size size] filename
Create a logical unit that can be registered with the STMF. For the -s option, size is an integer followed by one of the following let-
ters, to indicate a unit of size:
k kilobyte
m megabyte
g gigabyte
t terabyte
p petabyte
e exabyte
If you do not specify size, the size defaults to the size of filename.
The size specified can exceed the size of the file or device.
delete-lu lu_name
Deletes an existing logical unit that was created using sbdadm create-lu. This effectively unloads the logical unit from the STMF
framework. Any existing data on the logical unit remains intact.
import-lu lu_name
Imports and loads a logical unit into the STMF that was previously created using sbdadm create-lu and was since deleted from the STMF
using sbdadm delete-lu. On success, the logical unit is again made available to the STMF. filename is the filename used in the sbdadm
create-lu command for this logical unit.
list-lu
List all logical units that were created using the sbdadm create-lu command.
modify-lu [-s, --size size] lu_name | filename
Modifies attributes of an logical unit created using the sbdadm create-lu command. For the -s option, size is an integer value followed
by a unit specifier. The unit specifiers are as described above under create-lu. When this option is specified, the existing size of
the logical unit is changed to the new size.
The size specified can exceed the size of the file or device represented by lu_name.
OPERANDS
sbdadm use the following operands:
filename
Name of an existing file or a fully qualified path to a raw block device.
lu_name
The 32-byte hexadecimal representation of the logical unit.
EXAMPLES
Example 1 Creating a Logical Unit
The following series of commands creates a 10-gigabyte logical unit.
# touch /export/lun/0
# sbdadm create-lu -s 10g /export/lun/0
# sbdadm create-lu /dev/rdsk/c1t1d0s0
Example 2 Listing Logical Units
The following command lists all logical units.
# sbdadm list-lu
Found 2 LU(s)
GUID DATA SIZE SOURCE
-------------------------------- ----------- ------
6000ae4000144f21d92c47b0dd650002 10737352704 /export/lun/0
6000ae4000144f21d92c47b0de300032 134283264 /dev/rdsk/c1t1d0s0
EXIT STATUS
0
Successful completion.
non-zero
An error occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWstmfu |
+-----------------------------+-----------------------------+
|Interface Stability |Committed |
+-----------------------------+-----------------------------+
SEE ALSO
stmfadm(1M), attributes(5)
SunOS 5.11 12 Jun 2008 sbdadm(1M)