1. What does top do?
Junior- A.resume a job in the background / foreground
- B.show a live view of processes, CPU and memory
- C.show memory and swap usage, human-readable
- D.ask a process to terminate gracefully with SIGTERM
Linux · Processes & Perf interview questions
72 real Linux · Processes & Perf questions from the System Administration bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What does
Junior2. Which command will show a live view of processes, CPU and memory?
Junior- A.top
- B.free -h
- C.vmstat 1
- D.mpstat -P ALL 1
3. Which statement is correct?
Junior- A.top — show a live view of processes, CPU and memory
- B.top — report historical memory usage statistics
- C.top — print the PID(s) of a named process
- D.top — list processes with an open network connection on port 443
4. What does free -h do?
Junior- A.show memory and swap usage, human-readable
- B.list all running processes with CPU/memory usage
- C.print the PID(s) of a named process
- D.change the priority of a running process
5. Which command will show memory and swap usage, human-readable?
Junior- A.renice -n 5 -p PID
- B.free -h
- C.bg / fg
- D.top
6. Which statement is correct?
Junior- A.free -h — list background jobs of the current shell
- B.free -h — resume a job in the background / foreground
- C.free -h — show memory and swap usage, human-readable
- D.free -h — report per-CPU utilization every second
7. What does kill -9 PID do?
Junior- A.force-kill a process with SIGKILL (cannot be caught)
- B.report historical memory usage statistics
- C.report per-CPU utilization every second
- D.resume a job in the background / foreground
8. Which command will force-kill a process with SIGKILL (cannot be caught)?
Junior- A.bg / fg
- B.vmstat 1
- C.kill -9 PID
- D.sar -r
9. Which statement is correct?
Junior- A.kill -9 PID — start a command with lower CPU scheduling priority
- B.kill -9 PID — change the priority of a running process
- C.kill -9 PID — list all running processes with CPU/memory usage
- D.kill -9 PID — force-kill a process with SIGKILL (cannot be caught)
10. What does kill -15 PID do?
Mid- A.ask a process to terminate gracefully with SIGTERM
- B.change the priority of a running process
- C.report historical memory usage statistics
- D.show a live view of processes, CPU and memory
11. Which command will ask a process to terminate gracefully with SIGTERM?
Mid- A.kill -9 PID
- B.kill -15 PID
- C.lsof -i :443
- D.nice -n 10 cmd
12. Which statement is correct?
Mid- A.kill -15 PID — print the PID(s) of a named process
- B.kill -15 PID — ask a process to terminate gracefully with SIGTERM
- C.kill -15 PID — report CPU, memory and I/O statistics every second
- D.kill -15 PID — show memory and swap usage, human-readable
13. What does iostat -x do?
Mid- A.start a command with lower CPU scheduling priority
- B.show extended per-disk I/O statistics
- C.report historical memory usage statistics
- D.list all running processes with CPU/memory usage
14. Which command will show extended per-disk I/O statistics?
Mid- A.sar -r
- B.free -h
- C.iostat -x
- D.renice -n 5 -p PID
15. Which statement is correct?
Mid- A.iostat -x — start a command with lower CPU scheduling priority
- B.iostat -x — show extended per-disk I/O statistics
- C.iostat -x — print the PID(s) of a named process
- D.iostat -x — report per-CPU utilization every second
16. What does vmstat 1 do?
Mid- A.show extended per-disk I/O statistics
- B.print the PID(s) of a named process
- C.list background jobs of the current shell
- D.report CPU, memory and I/O statistics every second
17. Which command will report CPU, memory and I/O statistics every second?
Mid- A.ps aux
- B.vmstat 1
- C.kill -15 PID
- D.iostat -x
18. Which statement is correct?
Mid- A.vmstat 1 — show memory and swap usage, human-readable
- B.vmstat 1 — list all running processes with CPU/memory usage
- C.vmstat 1 — list background jobs of the current shell
- D.vmstat 1 — report CPU, memory and I/O statistics every second
19. What does lsof -i :443 do?
Mid- A.show extended per-disk I/O statistics
- B.list processes with an open network connection on port 443
- C.ask a process to terminate gracefully with SIGTERM
- D.list background jobs of the current shell
20. Which command will list processes with an open network connection on port 443?
Mid- A.vmstat 1
- B.sar -r
- C.renice -n 5 -p PID
- D.lsof -i :443
21. Which statement is correct?
Mid- A.lsof -i :443 — report per-CPU utilization every second
- B.lsof -i :443 — list processes with an open network connection on port 443
- C.lsof -i :443 — resume a job in the background / foreground
- D.lsof -i :443 — change the priority of a running process
22. What is load average?
Mid- A.a finished process whose parent hasn't reaped its exit status
- B.memory architecture where CPUs access local memory faster than remote
- C.kernel groups that limit and account for CPU/memory/IO per process set
- D.the average number of running + uninterruptible processes over 1/5/15 min
23. Which term means: "the average number of running + uninterruptible processes over 1/5/15 min"?
Mid- A.nohup
- B.swappiness
- C.SIGHUP
- D.load average
24. Which statement is correct?
Mid- A.load average — kernel groups that limit and account for CPU/memory/IO per process set
- B.load average — memory architecture where CPUs access local memory faster than remote
- C.load average — the average number of running + uninterruptible processes over 1/5/15 min
- D.load average — a finished process whose parent hasn't reaped its exit status
25. What is high load, low CPU?
Senior- A.runs a command immune to hangups so it survives logout
- B.signal 1, often used to make a daemon reload its config
- C.a symptom typically caused by I/O wait or D-state (uninterruptible) tasks
- D.the average number of running + uninterruptible processes over 1/5/15 min
26. Which term means: "a symptom typically caused by I/O wait or D-state (uninterruptible) tasks"?
Senior- A.OOM killer
- B.swappiness
- C.high load, low CPU
- D.load average
27. Which statement is correct?
Senior- A.high load, low CPU — a tunable (0–100) controlling how aggressively the kernel swaps
- B.high load, low CPU — the kernel mechanism that kills a process when memory is exhausted
- C.high load, low CPU — signal 1, often used to make a daemon reload its config
- D.high load, low CPU — a symptom typically caused by I/O wait or D-state (uninterruptible) tasks
28. What is OOM killer?
Mid- A.signal 1, often used to make a daemon reload its config
- B.a tunable (0–100) controlling how aggressively the kernel swaps
- C.runs a command immune to hangups so it survives logout
- D.the kernel mechanism that kills a process when memory is exhausted
29. Which term means: "the kernel mechanism that kills a process when memory is exhausted"?
Mid- A.OOM killer
- B.high load, low CPU
- C.cgroups
- D.zombie process
30. Which statement is correct?
Mid- A.OOM killer — kernel groups that limit and account for CPU/memory/IO per process set
- B.OOM killer — signal 1, often used to make a daemon reload its config
- C.OOM killer — the kernel mechanism that kills a process when memory is exhausted
- D.OOM killer — memory architecture where CPUs access local memory faster than remote
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