Operating System-Unix [3i Infotech Placement]: Sample Questions 60 - 62 of 78

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Question 60

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Describe in Detail

Essay▾

What is Fork swap?

Explanation

  • To create child process, fork () system call is invoked.
  • When the child process becomes read-to-run the memory is copied from swap device to the storage.
  • Child process swapping is done in main memory when the memory is available.
  • Process is swapped in when kernel schedules it.
  • fork () allocates entry in process table and assigns a unique PID to the child process.
  • fork () returns the PID of the child to the parent process and returns 0 to the child process.

Question 61

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Describe in Detail

Essay▾

What is ‘inode’ ?

Explanation

Understanding of Unix Inodes
  • Every file in UNIX has a unique number called Inode.
  • Number is associated with file information like user, group, ownership and access mode information.
  • Every inode stores the attributes and disk block location of the object՚s data.
  • Directories are lists of names assigned to inodes- self-entry contains a directory, its parent, and every children.
  • A files inode number is found from following command.

    Ls-i

  • If the inode number is known, the following command can get details of the file:

Question 62

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Describe in Detail

Essay▾

What is a Map?

Explanation

Understanding of Mapping in Memory
  • A map is an array containing the address of the free space in the swap device- allocable resources, and a count of number of the resource units available there.
  • Allows allocation of contiguous blocks of a resource.
  • Contains only one entry address and the total number of resources.
  • Kernel treats every unit of map a group of disk blocks.

A Map is also:

  • Utility to map texts from and to Unicode.
  • Or to map text from one character set representation to another.
  • An older utility for this purpose was record- unfortunately record does not support Unicode and eastern character sets.

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