Enhanced partition copy script (new & improved!) Post: 302448738

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Top Forums Shell Programming and Scripting Enhanced partition copy script (new & improved!) Post 302448738 by jwzumwalt on Friday 27th of August 2010 12:00:50 AM

08-27-2010

Registered User

I'm not sure I understand what you are asking but here is a bit of additional information that may or may not answer your question.

The partition information for an entire drive is kept in the MBR (master boot record). There is no separate or individual information block available. Therefore my program (and any other) that attempts to save the first 512 bytes of a partition (which is the mbr) for any partition other than the first will receive an error.

My program does not attempt to stop someone from saving an invalid MBR block on other partitions. dd is smart enough to notice that an attempt is being made to save the MBR of an invalid partition and will shoot out an error message, but it still saves the invalid 512 byte block.

This first example will work because the mbr is actualy at the start of partition 1

Code:

dd if=hda1 of=partition.mbr.img count=1 bs=512

This example will cause an error message because the 2nd partition does not have an mbr!

Code:

dd if=hda2 of=partition.mbr.img count=1 bs=512

My thinking is that there may be some special case that I am not aware of that a user may need that 512 byte block. So, I trust the users judgment.

In the future, I will place some type of error trap and give sa message to the user that explains what is going on.

I hope this information helps.

Jan Zumwalt

jwzumwalt

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service

service(8)						      System Manager's Manual							service(8)

NAME

       service - run a System V init script

SYNOPSIS

       service SCRIPT COMMAND [OPTIONS]

       service --status-all

       service --help | -h | --version

DESCRIPTION

       service	runs a System V init script in as predictable an environment as possible, removing most environment variables and with the current
       working directory set to /.

       The SCRIPT parameter specifies a System V init script, located in /etc/init.d/SCRIPT.  The  supported  values  of  COMMAND  depend  on  the
       invoked	script.  service passes COMMAND and OPTIONS to the init script unmodified.  All scripts should support at least the start and stop
       commands.  As a special case, if COMMAND is --full-restart, the script is run twice, first with the stop command, then with the start  com-
       mand.

       service --status-all runs all init scripts, in alphabetical order, with the status command.

EXIT CODES

       service calls the init script and returns the status returned by it.

FILES

       /etc/init.d
	      The directory containing System V init scripts.

ENVIRONMENT

       LANG, TERM
	      The only environment variables passed to the init scripts.

SEE ALSO

       /etc/init.d/skeleton,
       update-rc.d(8),
       init(8),
       invoke-rc.d(8).

								     Jan 2006								service(8)