Operating System [3i Infotech Placement]: Sample Questions 1 - 3 of 81

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Question 1

Operating System
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Describe in Detail

Essay▾

Brief about the directory representation in UNIX.

Explanation

  • A UNIX directory is a file containing a correspondence between filenames and inodes.
  • A directory is a special file, it is maintained by the kernel- Only kernel modifies directory, but processes can read directories.
  • The contents of a directory are a list of filename and inode number pairs.
  • Kernel makes two entries when new directories are created

‘.’

  • The directory itself.

‘. .’

  • Parent directory.
Kernel Makes Two Entries

Question 2

Operating System
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Write in Short

Short Answer▾

In what way the validity fault handler concludes?

Explanation

  • It sets the valid bit of the page by clearing the modify bit.
  • Maps the page to the memory
  • It recalculates the process priority.

Question 3

Operating System
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Describe in Detail

Essay▾

How are device represented in UNIX?

Explanation

  • Devices in UNIX are represented by files.
  • Each piece of hardware is a file.
  • Allows access to the hardware.
  • Device file is specified as ‘block special file’ with characteristics similar to a disk file.
  • Represents a device with characteristics similar to a keyboard.

Two types of devices are character devices and block devices.

ls-l/dev/zero

  • crw-rw-rw-1 root — — /dev character device

ls-l/dev/sdal

  • brw-rw — -1 root -/dev/sdal block device
Two Types of Devices

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