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8.What is wrong with the following command?

tar cvfb //dev/tape 20

You cannot use the c option with the b option.
The correct command should be tar -cvfb /dev/tape20.
The arguments are not in the same order as the corresponding modifiers.
The files to be backed up have not been specified.

Explanation: The command should read tar cvfb /dev/tape 20 / . The letters c, v, f and b are the 'modifiers'. The arguments are the options for the modifiers and should be in the same order as the modifiers. The c modifier is to create an archive. The v modifier is for verbose mode. The f modifier specifies the name of the tar file and so needs an 'argument' (in this case a tape drive called /dev/tape). The b modifier is used to set a block size and so needs an 'argument' (in this case 20). Note that the arguments following the modifiers are in the same order as the modifier. The "f" precedes the "b" modifier so the arguments have the device before the blocking factor. The arguments must be in the same order as the modifiers, which can sometimes cause a little confusion. After the modifiers and arguments have been entered, you need to enter the files to be backed up (in this case the root directory '/').

Reference: http://freebooks.boom.ru/view/LinuxUnleashed/ch45/759-762.html

Incorrect Answers
A: You can use the c option with the b option.
B: You don't need a hyphen (-) when specifying tar options. Furthermore, the files to be backed up haven't been specified.
D: The files to be backed up have been entered (the root partition '/'), but they are entered in the wrong place.

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