3i Infotech Papers: Sample Questions 724 - 725 of 1245

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Question number: 724

» Operating System » Unix

Essay Question▾

Describe in Detail

How do you create special files like named pipes and device files?

Explanation

  • Special files are created by the system call ‘mknod’.

  • Special file is created using following steps:

    • New inode is assigned by kernel.

    • Sets the file type as a pipe, directory or special file.

    • If the file type is a device file, major and minor device numbers are the two entries created.

  • Using the mknod command, special files are created:

    • mknod [options] name type [major minor].

  • Example:

    • For a disk, disk controller is the major device number and the disk is the minor device.

  • Unix example:

    • $ mknod < pipe name > p

Question number: 725

» Basic CS » Data Structures

MCQ▾

Question

Which is the simplest file structure?

Choices

Choice (4) Response

a.

Random

b.

Sequential

c.

Indexed

d.

None of the above

Answer

b.

Explanation

Define sequential files

Define Sequential Files

Define sequential files

  • Sequential is the simplest file structure.

  • Contains records or other elements stored in order based some identifying data like account number.

  • Method also called pile file method.

  • When a new record is inserted, it is placed at the end of the file.

  • In the case of any modification or deletion of record, the record will be searched in the memory blocks.

  • It found it is marked for deleting and new block of record is entered.

  • In order to locate the desired data, sequential files are read starting at the beginning.

  • Ideal for storage on a sequential access device magnetic tape or on a direct access device such as magnetic disk.

  • Contrast with random file.

Advantages of Sequential File Organization:

  • The design is very simple compared to other file organization.

  • Min effort involved in storing data.

  • Good method for report generation or statistical calculations.

  • Data stored in cheap magnetic tapes.

Disadvantages of Sequential File Organization:

  • Sorted file method always involves the effort for sorting the record.

  • Each time any insert, update, or delete transaction is performed, file is sorted.

  • Identifying the record, inserting, updating, deleting the record, always takes some time and may make system slow.