UNIX Question and Answer – Background and Foreground Processes
UNIX MCQ – Multiple Choice Questions for exam, interview, and Entrance Test
1. What command is used to move a background process to the foreground in UNIX?
a) fg
b) bg
c) move
d) switch
Answer: a) fg
Explanation: The fg command is used to move a background process to the foreground in UNIX.
2. In UNIX, which signal is sent to a process when it receives the Ctrl+Z key combination?
a) SIGINT
b) SIGTSTP
c) SIGSTOP
d) SIGHUP
Answer: b) SIGTSTP
Explanation: SIGTSTP is sent to a process when it receives the Ctrl+Z key combination, suspending it in UNIX.
3. What is the purpose of the disown command in UNIX?
a) Suspend a process
b) Terminate a process
c) Remove a process from the shell’s job table
d) Bring a process to the foreground
Answer: c) Remove a process from the shell’s job table
Explanation: The disown command is used to remove a process from the shell’s job table in UNIX.
4. In UNIX, what happens to a background process when the shell session ends?
a) It is terminated
b) It is paused
c) It is resumed
d) It is moved to the foreground
Answer: a) It is terminated
Explanation: Background processes are terminated when the shell session ends in UNIX.
5. Which command is used to send a signal to resume a suspended background process in UNIX?
a) fg
b) kill -CONT
c) resume
d) unstop
Answer: b) kill -CONT
Explanation: The kill command with the -CONT option is used to send a signal to resume a suspended background process in UNIX.
6. In UNIX, what is the purpose of the nice command?
a) Change the ownership of a process
b) Change the priority of a process
c) Change the group of a process
d) Change the name of a process
Answer: b) Change the priority of a process
Explanation: The nice command is used to change the priority of a process in UNIX.
7. What signal is sent to a process when the Ctrl+D key combination is pressed in UNIX?
a) SIGINT
b) SIGTSTP
c) SIGQUIT
d) SIGHUP
Answer: d) SIGHUP
Explanation: SIGHUP is sent to a process when the Ctrl+D key combination is pressed in UNIX.
8. What is the primary purpose of the bg command in UNIX?
a) Move a background process to the foreground
b) Move a foreground process to the background
c) Terminate a background process
d) Display a list of background jobs
Answer: b) Move a foreground process to the background
Explanation: The bg command is used to move a suspended foreground process to the background in UNIX.
9. In UNIX, what happens to a foreground process when it receives the SIGTERM signal?
a) It is suspended
b) It is resumed
c) It is terminated
d) It is sent to the background
Answer: c) It is terminated
Explanation: A foreground process is terminated when it receives the SIGTERM signal in UNIX.
10. Which command is used to send a signal to a process by its name in UNIX?
a) pskill
b) pkill
c) killbyname
d) signalbyname
Answer: b) pkill
Explanation: The pkill command is used to send a signal to a process by its name in UNIX.
11. In UNIX, what is the primary purpose of the killall command?
a) Terminate a process by name
b) Terminate all running processes
c) Bring all processes to the foreground
d) Suspend all running processes
Answer: a) Terminate a process by name
Explanation: The killall command is used to terminate a process by name in UNIX.
12. What signal is sent to a process when the Ctrl+C key combination is pressed in UNIX?
a) SIGINT
b) SIGTERM
c) SIGQUIT
d) SIGHUP
Answer: a) SIGINT
Explanation: SIGINT is sent to a process when the Ctrl+C key combination is pressed in UNIX.
13. In UNIX, what is the purpose of the renice command?
a) Change the name of a process
b) Change the priority of a process
c) Change the owner of a process
d) Change the group of a process
Answer: b) Change the priority of a process
Explanation: The renice command is used to change the priority of a process in UNIX.
14. What signal is sent to a process when the Ctrl+D key combination is pressed in UNIX?
a) SIGKILL
b) SIGTERM
c) SIGHUP
d) SIGQUIT
Answer: c) SIGHUP
Explanation: SIGHUP is sent to a process when the Ctrl+D key combination is pressed in UNIX.
15. In UNIX, what is the primary purpose of the trap command?
a) Run a command in the background
b) Handle signals received by the shell or scripts
c) Display system load information
d) Manage user sessions
Answer: b) Handle signals received by the shell or scripts
Explanation: The trap command is used to handle signals received by the shell or scripts in UNIX.
16. What is the purpose of the wait command in UNIX?
a) Suspend a process until it receives a signal
b) Terminate a process
c) Bring a process to the foreground
d) Wait for background processes to complete
Answer: d) Wait for background processes to complete
Explanation: The wait command is used to wait for background processes to complete in UNIX.
17. Which command is used to send a signal to stop a process in UNIX?
a) stop
b) kill -STOP
c) suspend
d) pause
Answer: b) kill -STOP
Explanation: The kill command with the -STOP option is used to send a signal to stop a process in UNIX.
18. In UNIX, what is the purpose of the renice command?
a) Change the name of a process
b) Change the priority of a process
c) Change the owner of a process
d) Change the group of a process
Answer: b) Change the priority of a process
Explanation: The renice command is used to change the priority of a process in UNIX.
19. What signal is sent to a process when the Ctrl+D key combination is pressed?
a) SIGKILL
b) SIGTERM
c) SIGHUP
d) SIGQUIT
Answer: c) SIGHUP
Explanation: SIGHUP is the signal sent to a process when the Ctrl+D key combination is pressed in UNIX.
20. What is the purpose of the trap command in UNIX?
a) Run a command in the background
b) Handle signals received by the shell or scripts
c) Display system load information
d) Manage user sessions
Answer: b) Handle signals received by the shell or scripts
Explanation: The trap command is used to handle signals received by the shell or scripts in UNIX.
21. In UNIX, what is the significance of the & symbol when used with a command?
a) It redirects output to a file
b) It runs the command as a background process
c) It runs the command as a foreground process
d) It pipes output to another command
Answer: b) It runs the command as a background process
Explanation: The & symbol is used to run a command as a background process in UNIX.
22. What is the purpose of the wait command in UNIX?
a) Suspend a process until it receives a signal
b) Terminate a process
c) Bring a process to the foreground
d) Wait for background processes to complete
Answer: d) Wait for background processes to complete
Explanation: The wait command is used to wait for background processes to complete in UNIX.
23. Which command is used to send a signal to stop a process in UNIX?
a) stop
b) kill -STOP
c) suspend
d) pause
Answer: b) kill -STOP
Explanation: The kill command with the -STOP option is used to send a signal to stop a process in UNIX.
24. In UNIX, what is the purpose of the renice command?
a) Change the name of a process
b) Change the priority of a process
c) Change the owner of a process
d) Change the group of a process
Answer: b) Change the priority of a process
Explanation: The renice command is used to change the priority of a process in UNIX.
25. What signal is sent to a process when the Ctrl+D key combination is pressed?
a) SIGKILL
b) SIGTERM
c) SIGHUP
d) SIGQUIT
Answer: c) SIGHUP
Explanation: SIGHUP is the signal sent to a process when the Ctrl+D key combination is pressed in UNIX.
26. Which command is used to display the process ID (PID) of a running process in UNIX?
a) pid
b) pidof
c) psid
d) getpid
Answer: b) pidof
Explanation: The pidof command is used to display the process ID (PID) of a running process in UNIX.
27. In UNIX, what happens to a background process when the shell session is suspended using Ctrl+Z?
a) It continues running in the background
b) It is paused and moved to the foreground
c) It is terminated
d) It is resumed automatically
Answer: b) It is paused and moved to the foreground
Explanation: When the shell session is suspended using Ctrl+Z, the background process is paused and moved to the foreground in UNIX.
28. What is the purpose of the kill command with the -9 option in UNIX?
a) Pause a process
b) Terminate a process immediately
c) Send a stop signal to a process
d) Change the priority of a process
Answer: b) Terminate a process immediately
Explanation: The kill command with the -9 option is used to terminate a process immediately in UNIX.
29. In UNIX, what does the term “foreground” refer to in the context of processes?
a) Processes that are running in the background
b) Processes that are running in the terminal and are interactive
c) Processes that are paused
d) Processes that are running with elevated privileges
Answer: b) Processes that are running in the terminal and are interactive
Explanation: In UNIX, foreground processes refer to processes that are running in the terminal and are interactive.
30. Which command is used to send a signal to a process by its name in UNIX?
a) signal
b) killall
c) pkill
d) psignal
Answer: c) pkill
Explanation: The pkill command is used to send a signal to a process by its name in UNIX.
31. In UNIX, what is the purpose of the renice command?
a) Change the name of a process
b) Change the priority of a process
c) Change the owner of a process
d) Change the group of a process
Answer: b) Change the priority of a process
Explanation: The renice command is used to change the priority of a process in UNIX.
32. What signal is sent to a process when the Ctrl+C key combination is pressed in UNIX?
a) SIGKILL
b) SIGTERM
c) SIGHUP
d) SIGINT
Answer: d) SIGINT
Explanation: SIGINT is sent to a process when the Ctrl+C key combination is pressed in UNIX.
33. What is the purpose of the nohup command in UNIX?
a) Run a command in the background and ignore hangup signals
b) Run a command with elevated privileges
c) Run a command in the foreground
d) Run a command without any output
Answer: a) Run a command in the background and ignore hangup signals
Explanation: The nohup command is used to run a command in the background and ignore hangup signals in UNIX.
34. In UNIX, what does the term “background” refer to in the context of processes?
a) Processes that are running in the terminal and are interactive
b) Processes that are paused
c) Processes that are running with elevated privileges
d) Processes that are running independently of the terminal
Answer: d) Processes that are running independently of the terminal
Explanation: In UNIX, background processes refer to processes that are running independently of the terminal.
35. Which command is used to send a signal to a process by its process ID (PID) in UNIX?
a) kill
b) signal
c) psignal
d) killall
Answer: a) kill
Explanation: The kill command is used to send a signal to a process by its process ID (PID) in UNIX.
36. In UNIX, what is the purpose of the bg command?
a) Bring a background process to the foreground
b) Move a suspended process to the background
c) Terminate a background process
d) Suspend a foreground process
Answer: b) Move a suspended process to the background
Explanation: The bg command is used to move a suspended process to the background in UNIX.
37. What signal is sent to a process when the Ctrl+D key combination is pressed in UNIX?
a) SIGINT
b) SIGTSTP
c) SIGHUP
d) SIGQUIT
Answer: c) SIGHUP
Explanation: SIGHUP is sent to a process when the Ctrl+D key combination is pressed in UNIX.
38. In UNIX, what is the purpose of the fg command?
a) Move a process to the foreground
b) Move a process to the background
c) Terminate a process
d) Display a list of background jobs
Answer: a) Move a process to the foreground
Explanation: The fg command is used to move a process to the foreground in UNIX.
39. What is the significance of the $! symbol in UNIX shell scripting?
a) It represents the process ID (PID) of the last background command
b) It represents the process ID (PID) of the last foreground command
c) It represents the exit status of the last command
d) It represents the number of arguments passed to a command
Answer: a) It represents the process ID (PID) of the last background command
Explanation: The $! symbol represents the process ID (PID) of the last background command in UNIX shell scripting.
40. Which command is used to send a signal to a process by its name in UNIX?
a) psignal
b) signal
c) pkill
d) killall
Answer: c) pkill
Explanation: The pkill command is used to send a signal to a process by its name in UNIX.
41. In UNIX, what does the term “foreground” refer to in the context of processes?
a) Processes that are running in the background
b) Processes that are running in the terminal and are interactive
c) Processes that are paused
d) Processes that are running with elevated privileges
Answer: b) Processes that are running in the terminal and are interactive
Explanation: In UNIX, foreground processes refer to processes that are running in the terminal and are interactive.
42. Which command is used to display the process ID (PID) of a running process in UNIX?
a) pid
b) pidof
c) psid
d) getpid
Answer: b) pidof
Explanation: The pidof command is used to display the process ID (PID) of a running process in UNIX.
43. In UNIX, what happens to a background process when the shell session is suspended using Ctrl+Z?
a) It continues running in the background
b) It is paused and moved to the foreground
c) It is terminated
d) It is resumed automatically
Answer: b) It is paused and moved to the foreground
Explanation: When the shell session is suspended using Ctrl+Z, the background process is paused and moved to the foreground in UNIX.
44. What is the purpose of the kill command with the -9 option in UNIX?
a) Pause a process
b) Terminate a process immediately
c) Send a stop signal to a process
d) Change the priority of a process
Answer: b) Terminate a process immediately
Explanation: The kill command with the -9 option is used to terminate a process immediately in UNIX.
45. In UNIX, what does the term “background” refer to in the context of processes?
a) Processes that are running in the terminal and are interactive
b) Processes that are paused
c) Processes that are running with elevated privileges
d) Processes that are running independently of the terminal
Answer: d) Processes that are running independently of the terminal
Explanation: In UNIX, background processes refer to processes that are running independently of the terminal.
46. Which command is used to send a signal to a process by its name in UNIX?
a) signal
b) killall
c) pkill
d) psignal
Answer: c) pkill
Explanation: The pkill command is used to send a signal to a process by its name in UNIX.
47. In UNIX, what is the purpose of the renice command?
a) Change the name of a process
b) Change the priority of a process
c) Change the owner of a process
d) Change the group of a process
Answer: b) Change the priority of a process
Explanation: The renice command is used to change the priority of a process in UNIX.
48. What signal is sent to a process when the Ctrl+C key combination is pressed in UNIX?
a) SIGKILL
b) SIGTERM
c) SIGHUP
d) SIGINT
Answer: d) SIGINT
Explanation: SIGINT is sent to a process when the Ctrl+C key combination is pressed in UNIX.
49. What is the purpose of the nohup command in UNIX?
a) Run a command in the background and ignore hangup signals
b) Run a command with elevated privileges
c) Run a command in the foreground
d) Run a command without any output
Answer: a) Run a command in the background and ignore hangup signals
Explanation: The nohup command is used to run a command in the background and ignore hangup signals in UNIX.
50. In UNIX, what does the term “foreground” refer to in the context of processes?
a) Processes that are running in the background
b) Processes that are running in the terminal and are interactive
c) Processes that are paused
d) Processes that are running with elevated privileges
Answer: b) Processes that are running in the terminal and are interactive
Explanation: In UNIX, foreground processes refer to processes that are running in the terminal and are interactive.
