System Programming Test 2015

1. Which of the following system calls can be used to send a message via a connected socket?

Answers:

• send

• sendto

• sendmsg

• write

2. Which of the following methods can be used as a communication mechanism between two unrelated processes?

Answers:

• A pipe using the pipe system call.

• A named pipe using the mknod system call.

• Named sockets.

• Signals.

3. Which of the following are true of Unix system calls?

Answers:

• System calls are executed in "User" context.

• The routine "malloc" which is used for allocating memory is a system call.

• A new file can be created using the "open" system call.

• If two processes are executing the "write" system call simultaneously, they are serialized by the operating system.

• The "read" system call will never be blocked.

4. Which of the following Linux commands can be used to identify the processes consuming maximum resources (CPU, Memory)?

Answers:

• ps

• top

• lsof

• vmstat

5. Which of the following signals are used by the Unix shell to implement job control?

Answers:

• SIGHUP

• SIGSTOP

• SIGCONT

• SIGINT

6. Which of the following environment variables specifies the shared library search path?

Answers:

• SHARED_LIBRARIES

• SHLIB_PATH

• LD_LIBRARY_PATH

• LIBRARIES

7. Which of the following statements are true?

Answers:

• "wc -l" can be used to count the number of lines in the input.

• "find . -name '*.txt' -exec rm {} \;" removes all ".txt" files in the current directory hierarchy.

• "cc -x " can be used to generate the assembler listing of the C program file.

• "set -x" can be used within a ksh shell script to generate listing of shell commands while they are being executed.

8. Which of the following utilities would you use on a standard Linux system to debug a running application?

Answers:

• gdb.

• ltrace.

• strace.

• ptrace.

9. Which of the following can be used to inspect the system call arguments of a Linux process?

Answers:

• strace

• gdb

• adb

• mdb

10. Which of the following methods can be used to allocate and use memory on a Unix system?

Answers:

• brk

• sbrk

• malloc

• calloc

11. Which of the following utilities is used to generate a core file of a process on Linux?

Answers:

• gdb

• strace

• gcore

• objdump

12. Which of the following can be used to debug the process "123" and program "test" on a Linux system?

Answers:

• adb test 123

• gdb test 123

• strace 123

• strace -f -p 123

13. If a process has locked a System V Semaphore and receives a SIGKILL signal, which of the following is true?

Answers:

• The process can catch the signal and drop the semaphore before terminating.

• The process terminates without releasing the semaphore.

• The semaphore is released if the process had specified SEM_UNDO during creation.

• The signal is deferred until the semaphore is released.

14. Which of the following utilities is used to search out regular expressions in the input?

Answers:

• cat

• grep

• head

• tail

15. What does the command "mknod temp p" do?

Answers:

• It creates a named pipe.

• It creates directory nodes "temp" and "p".

• It creates pipes "temp" and "p"

16. Threads created via pthread_create need to first set up shared memory

using shmop before they can share data.

Answers:

• True

• False

17. What does the "open" system call return to the caller?

Answers:

• 0 on success and -1 on error.

• File descriptor.

• An integer greater than or equal to 0 on success and -1 on error.

• Always 0.

18. What is the effect of a process executing an unlink system call while another process has opened the same file?

Answers:

• The unlink system call will fail.

• The unlink system call will succeed and the other process will be terminated.

• The unlink system call will be blocked until the other process has closed all references to the file.

• The unlink system call will succeed.

19. Which of the following signals cannot be ignored by a process?

Answers:

• SIGHUP

• SIGINT

• SIGTERM

• SIGKILL

20. Ignoring the setup cost for each of the System V IPC mechanisms, which of the following is the most efficient?

Answers:

• System V, Messages.

• System V, Shared Memory

• System V, Semaphores

• Sockets

21. What command is used to list the shared libraries used by an executable?

Answers:

• ldconfig

• ld

• ldd

• ls

22. What does the following command do to the process with pid 12345?

"kill -9 12345".

Answers:

• It sends the INT signal causing the process to be interrupted.

• It sends the STOP signal causing the process to be stopped.

• It sends the KILL signal causing the process to be killed.

• It sends the HUP singal causing the process to hangup.

23. Which of the following system calls is the most memory efficient method of reading a file?

Answers:

• readv

• read

• mmap

• fcntl

24. Which of the following commands generates a listing of the system calls being executed by a program on Solaris?

Answers:

• ltrace

• tusc

• strace

• truss

25. What is the effect of issuing a "$c" command at the adb prompt during a debugging session on a Solaris 9 system?

Answers:

• It generates a listing of the stack trace.

• It causes the debugger to continue.

• It drops to the shell.

• It prints the register contents.

26. Which of the following sequences prints all the second column fields of an input file "values.txt"?

Answers:

• awk "print $2" values.txt

• awk '{print $2}' values.txt

• awk '{print #2}' values.txt

• cut -2 values.txt

27. Which of the following system calls increases the process priority?

Answers:

• priority

• nice

• ulimit

• fcntl

28. Which of the following is true of Unix system calls?

Answers:

• System calls cannot be executed by regular users.

• System calls are executed in the user context.

• System calls are executed in the kernel context.

• System calls cause a process switch.

29. Which of the following gdb commands can be used to obtain the stack

trace of all the threads of a multi threaded program running on Linux?

Answers:

• bt

• ::stack

• $C

• thread apply all bt

30. If a process is hung in the kernel context, sending it a SIGKILL will _____.

Answers:

• kill the process immediately.

• be ignored by the Operating System.

• be delivered when the process switches back to the user context.

31. The library routine printf does not use any system calls.

Answers:

• True.

• False.

32. Which of the following gcc compiler options turns on optimization?

Answers:

• optimize

• O

• Opt

• -S

33. Which of the following options of the compiler is turned on to generate additional debug information (like the source code) for debugging an application?

Answers:

• O

• S

• E

• g

34. Which of the following options specifies a non standard library path during linking?

Answers:

• -l

• -L

• -o

• -g

35. Which of the following shell operators redirects the standard input of the command being executed?

Answers:

• <

• >

• %

• @

36. Which library routine is used to translate the numeric system call error code to a human readable text error message?

Answers:

• sprintf

• exit

• error

• perror

37. Which of the following IPC message operations is performed to setup communication between arbitrary processes?

Answers:

• msgctl

• msgsnd

• msgrcv

• msgget

38. What is the effect of executing the following system call on the file "test.txt"?

open("test.txt", O_TRUNC)

Answers:

• The file is truncated to the nearest block size before returning.

• The file is created before returning.

• The file is opened.

• If test.txt exists, the file is truncated to 0 bytes before returning.

39. How does a programmer distinguish a child from its parent process following a fork system call?

Answers:

• The system call returns 0 to the child and 1 to the parent.

• The system call returns 0 to the parent and the pid of the parent to the child.

• The system call returns 0 to the child and the pid of the child to the parent.

• There is no way to distinguish a child from its parent.

40. Which of the following libraries provides the POSIX thread implementation on Solaris?

Answers:

• libpthread

• libthread

• libnptl

• libc

41. Which of the following IPC shared memory sequences is correct?

Answers:

• shmctl, shmat, shmdt

• shmget, shmat, shmdt

• shmctl, shmget, shmat, shmdt

• shmat, shmdt

42. How is the value of the shell environment variable IFS changed to comma (',')?

Answers:

• IFS=','; export IFS

• $IFS=','; export IFS

• IFS=','; export $IFS

• $IFS=','

43. Which of the compiler options generates an assembler output file?

Answers:

• -O

• -a

• -S

• -g

44. What does the '-pg' option of the Unix compiler do?

Answers:

• It turns on the profiling of the executable code.

• It generates an assembler listing of the code.

• It turns on the generation of the optimized code.

• It prints the different function call graphs.

45. Shared libraries increase an application's disk size?

Answers:

• True.

• False.

46. Which of the following redirects the standard error output of a command to the log file "error.log"?

Answers:

• "2>error.log"

• "2

• ">error.log"

• "|error.log"

47. What are the typical system calls the Unix shell invokes when it

has to execute a new command?

Answers:

• open, read, close.

• open, fork, exec.

• ioctl.

48. Which system call is used to send a signal to another process?

Answers:

• signal

• kill

• socket

• ioctl

49. Which of the following shell commands is useful in single stepping through a shell script?

Answers:

• set -x

• echo

• trap

• DEBUG

50. Which of the following commands can be used to generate a listing of all the shared libraries that an executable needs?

Answers:

• ld

• ldd

• ls

• ln

51. What is the default file descriptor used for the error outputs of a process?

Answers:

• 0

• 1

• 2

• -1

52. Which of the following commands can be used on a Linux system to kill process 8977 and all its children?

Answers:

• kill -term 8977

• kill -kill 8977

• kill -stop 8977

• kill -int 8977

53. Which of the following commands can be used on a Linux system to configure a network interface (card)?

Answers:

• ifconfig

• ipconfig

• netstat -c

• route

54. Which of the following commands can be used to list all the active TCP connections only on a Linux system?

Answers:

• netstat -r

• netstat -t

• iptables -L

• route

55. Which of the following ksh trap sequences causes the function 'handler' to be executed when the script exits?

Answers:

• trap handler EXIT

• trap EXIT handler

• set handler EXIT

• trap handler exit

56. How many bytes of a file of size 1023 will be read by the following piece of code?

  char buf[256];

  <snip>

  while (read(fd, buf, 256)) {

           /* Take some action */

  }

  <snip>

Answers:

• 1024

• 1023

• 0

• 768

57. What is the effect of setting the "sticky" bit on an application's executable image?

Answers:

• It causes the system to load the program faster the next time it runs.

• It causes the system to fail all unlink system call requests on the image.

• It causes the system to preload the application's image into the system RAM.

• It causes the system to grant the application owner's privileges to other users if they try to run the application.

58. A C program "domath.c" utilizes the math library. Which of

the following commands correctly creates the corresponding executable

"domath"?

Answers:

• cc -o domath domath.c

• cc -o domath domath.c -L /usr/lib -lmath

• cc -o domath domath.c -lm

• cc -o domath domath.c -Lmath

59. Which of the following sequences creates a socket based connection for communication?

Answers:

• open, listen, accept

• open, accept, listen

• socket, connect, accept, listen

• socket, connect, listen, accept

60. What does the open system call return upon success?

Answers:

• A non zero value, which is the file descriptor.

• Zero.

• A positive integer which is the file descriptor.

• The pointer to the FILE structure of the open file.

61. If a process executes the following C code on a Linux system, what is the outcome?

<snip>

        char        *cp = 0, c = *cp;

<snip>

Answers:

• The process executes the code without errors.

• The process is killed with a SIGSEGV.

• The process is killed with a SIGBUS.

• The process is killed with a SIGKILL.

62. On Linux, the pthread_create interface does not use the fork system call to create threads.

Answers:

• True.

• False.

63. Which of the following shell parameters contains the return value of the previously executed shell command?

Answers:

• $*

• $$

• $?

• $!

64. Which of the following calls is used to initiate a socket connection to a target address?

Answers:

• socket

• connect

• accept

• listen

65. Which of the following gcc options can be used to generate a position independent code on a Linux system?

Answers:

• -pic

• +z

• -b

• -mshared

66. Which of the following commands can be used to list all the active TCP connections on a Linux system?

Answers:

• netstat -r

• netstat -t

• iptables -L

• route

67. What is the network byte order in Unix?

Answers:

• Little Endian

• Big Endian

• It is negotiated during connection.

• It is undefined.

68. Which of the following segments within the process address space are unique to each thread?

Answers:

• code.

• data.

• stack.

• bss.

69. How do threads created using pthread library share data between themselves efficiently?

Answers:

• They use one of the standard interprocess communication methods.

• They use sockets.

• They don't need any special mechanism as they share the data segment.

• They use shared memory.

70. By convention, which of the following signals causes a daemon to reload its configuration?

Answers:

• SIGHUP

• SIGKILL

• SIGINT

• SIGCONT

71. Which of the following block sizes results in the best read/write performance for an IO intensive application?

Answers:

• 8192

• 4096

• 2048

• 1024

72. What is the name of the standard linker on Unix?

Answers:

• cc

• ldd

• ld

• ls

73. Which of the following is employed by the operating system to speed up file IO on a Solaris system.

Answers:

• Inode Cache

• DNLC

• Buffer Cache

• Page Cache

74. How is the stack trace of all the threads in a multi threaded Linux application obtained?

Answers:

• strace -f -p <procid>

• "backtrace" at the gdb prompt.

• "thread apply all ::stack" at the gdb prompt.

• "thread apply all backtrace" at the gdb prompt.

75. Which of the following creates an IPC message channel?

Answers:

• id = msgget(key, 0700|IPC_CREAT);

• id = msgget(key, 0700, IPC_CREAT);

• id = msgctl(key, 0700|IPC_CREAT);

• id = msgctl(key, IPC_CREAT, 0700);

76. Which of the following system calls can be used to get the metadata of a file?

Answers:

• open

• stat

• fcntl

• ioctl

77. Which of the following commands can be used to create a static (archive) library?

Answers:

• tar

• ar

• ld

• gcc

78. Which of the following system calls is specific to debugging?

Answers:

• truss

• fcntl

• strace

• ptrace

79. Which of the following commands can be used to compile a C file called "test.c" into an executable called "test"?

Answers:

• cc -o test test.c

• cc -g -S test.c

• cc test test.c

• cc -E test.c

80. Which of the following IO mechanisms allows greater performance to concurrent IO-intensive applications?

Answers:

• Memory Mapped IO

• Read Ahead

• Direct IO (Filesystem locking is skipped)

• Async IO.

81. What is the outcome of attempting an ioctl system call on a block device file?

Answers:

• The system returns ENOTTY.

• The ioctl succeeds and returns 0.

• The system returns EIO.

• The system returns ENXIO.

82. Which of the following system calls can be used to create device special files?

Answers:

• open

• mkfs

• touch

• mknod

83. If a process is terminated due to a SEGFAULT on a Solaris 9 system, what is the name of the core file that is created?

Answers:

• core

• corefile

• memdump

• coredump

84. Which of the following socket system calls creates a Unix Domain Socket connection?

Answers:

• socket(PF_UNIX, SOCK_STREAM, protocol)

• socket(PF_INET, SOCK_DGRAM, protocol)

• socket(PF_IPX, SOCK_RAW, protocol)

• socket(PF_LOCAL, SOCK_STREAM, protocol)

85. Which of the following system calls creates a named socket?

Answers:

• creat

• mknod

• bind

• socket

86. Which of the following shell operators is used to send the standard output of the first command to the standard input of the second command?

Answers:

• &

• ^

• >

• |

87. Which of the following C headers needs to be included for socket programming?

Answers:

• <socket.h>

• <sys/socket.h>

• <stdio.h>

• <stdlib.h>

88. Where are the DNS and search domains specified?

Answers:

• /etc/fstab

• /etc/nsswitch.conf

• /etc/resolv.conf

• /etc/hosts-

89. A process opens a file and forgets to close the file descriptor when it

exits. What is the result?

Answers:

• It results in a resource leak.

• The OS calls exit on behalf of the process before it terminates the process resulting in all the resources being reclaimed.

• The OS garbage collector recovers the descriptor.

90. If a write system call fails and if errno is set to EFAULT, what does it signify?

Answers:

• The system encountered an IO error while doing the write.

• The file descriptor was illegal.

• The write buffer is not legal.

• The file was removed by another process while this write was being attempted.

91. Which of the following commands can be used to install the native software package SOFTpkg on a Solaris system?

Answers:

• tar -xvf SOFTpkg

• swinstall -s `pwd` SOFTpkg

• rpm -i SOFTpkg

• pkgadd -d . SOFTpkg

92. How do two threads synchronize access to shared data in a multi threaded application?

Answers:

• mutex_enter

• pthread_rwlock

• pthread_key_create

• pthread_mutex_lock

93. Which of the following system calls can be used to change process scheduling priority?

Answers:

• priority

• nice

• ulimit

• fcntl

94. Which of the following compiler options links the standard math library to the executable?

Answers:

• -link -mathlib

• -linkmath

• -L math

• -lm