A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

31. Which of the following statement is not correct with reference to cron daemon in UNIX O.S?
a. The cron daemon is the standard tool for running commands on a pre-determined schedule.
b. It starts when the system boots and runs as long as the system is up.
c. Cron reads configuration files that contain list of command lines and the times at which they invoked.
d. Crontab for individual users are not stored.
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Answer: (d).Crontab for individual users are not stored.

32. In Unix, files can be protected by assigning each one a 9-bit mode called rights bits. Now, consider the following two statements:

I. A mode of 641 (octal) means that the owner can read and write the file, other members of the owner’s group can read it, and users can execute only.
II. A mode of 100 (octal) allows the owner to execute the file, but prohibits all other access.

Which of the following options is correct with reference to above statements?
a. Only I is correct
b. Only II is correct
c. Both I and II are correct
d. Both I and II are incorrect
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Answer: (c).Both I and II are correct

33. In Unix, the login prompt can be changed by changing the contents of the file ...............
a. contrab
b. init
c. gettydefs
d. inittab
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Answer: (c).gettydefs

34. A unix file system has 1-KB blocks and 4-byte disk addresses. What is the maximum file size if i-nodes contain 10 direct entries and one single, double and triple indirect entry each?
a. 32 GB
b. 64 GB
c. 16 GB
d. 1 GB
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Answer: (c).16 GB

35. In Unix operating system, special files are used to :
a. buffer data received in its input from where a process reads
b. provide a mechanism to map physical device to file names
c. store list of file names plus pointers associated with i-nodes
d. store information entered by a user application program or utility program
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Answer: (b).provide a mechanism to map physical device to file names

36. Match the following in Unix file system :

List - I                         List - II
(a) Boot block               (i) Information about file system
(b) Super block            (ii) Information about file
(c) Inode table              (iii) Storage space
(d) Data block               (iv) Code for making OS ready

Codes :
      (a)  (b)  (c)  (d)
a. (iv)  (i)   (ii)  (iii)
b. (i)    (iii) (ii)  (iv)
c. (iii)  (i)   (ii)  (iv)
d. (iv)  (ii)  (i)   (iii)
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Answer: (a).(iv)  (i)   (ii)  (iii)

37. In Unix, the command to enable execution permission for file “mylife” by all is ................
a. Chmod ugo+X myfile
b. Chmod a+X myfile
c. Chmod +X myfile
d. All of the above
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Answer: (d).All of the above

38. What will be the output of the following Unix command ?

$rm chap0\[1 - 3\]
a. Remove file chap0[1 - 3]
b. Remove file chap01, chap02, chap03
c. Remove file chap\[1 - 3\]
d. None of the above
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Answer: (a).Remove file chap0[1 - 3]

39. Which of the following out commands will output "onetwothree"?
a. for val; do echo-n $val; done < one two three
b. for one two three; do echo-n-; done
c. for n in one two three; do echo-n $n; done
d. for n in one two three {echo-n $n}
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Answer: (c).for n in one two three; do echo-n $n; done

40. Assume that an implementation of Unix operating system uses i-nodes to keep track of data blocks allocated to a file. It supports 12 direct block addresses, one indirect block address and one double indirect block address. The file system has 256 bytes block size and 2 bytes for disk block address. The maximum possible size of a file in this system is
a. 16 MB
b. 16 KB
c. 70 KB
d. None of the above
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Answer: (d).None of the above

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