Which of the following commands overwrites the bootloader located on /dev/sda without overwriting the partition table or any data following it?
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A. B. C. D.C
The command to overwrite the bootloader located on /dev/sda without overwriting the partition table or any data following it is:
C. dd if=/dev/zero of=/dev/sda bs=440 count=1
Explanation:
The dd command is a low-level utility in Linux used to copy and convert data. The syntax for dd command is as follows:
dd [OPTION]... [INPUT [OUTPUT]]
In the above syntax, the input file (if) and output file (of) are specified using the respective options.
To overwrite the bootloader located on /dev/sda without overwriting the partition table or any data following it, we need to write zeros to the first 440 bytes of the disk, which is where the bootloader code resides.
Option A: dd if=/dev/zero of=/dev/sda bs=512 This command will write zeros to the entire disk (/dev/sda) block by block, with a block size (bs) of 512 bytes. This will overwrite the partition table and all data following it, not just the bootloader code.
Option B: dd if=/dev/zero of=/dev/sda bs=512 count=1 This command will write zeros to the first block (512 bytes) of the disk (/dev/sda). While it will not overwrite the partition table, it will overwrite the bootloader code as well as any other data in that first block.
Option C: dd if=/dev/zero of=/dev/sda bs=440 count=1 This command will write zeros to the first 440 bytes of the disk (/dev/sda). This will overwrite only the bootloader code, leaving the partition table and any data following it intact.
Option D: dd if=/dev/zero of=/dev/sda bs=440 This command will write zeros to the first 440 bytes of the disk (/dev/sda), but it will continue until the end of the disk. This will overwrite the partition table and all data following it, not just the bootloader code.
Therefore, option C is the correct answer.