Important interview questions on OS (Operating Systems)

OS Concepts
o What do the system calls fork(), vfork(), exec(), wait(), waitpid() do?
Whats a Zombie process? Whats the difference between fork() and
vfork()?
o How does freopen() work? *
o What are threads? What is a lightweight process? What is a heavyweight
process? How different is a thread from a process? *
o How are signals handled? *
o What is a deadlock? *
o What are semaphores? *
o What is meant by context switching in an OS?*
o What is Belady's anomaly?
o What is thrashing?*
o What are short-, long- and medium-term scheduling?
o What are turnaround time and response time?
o What is the Translation Lookaside Buffer (TLB)?
o What is cycle stealing?
o What is a reentrant program?
o When is a system in safe state?
o What is busy waiting?
o What is pages replacement? What are local and global page
replacements?*
o What is meant by latency, transfer and seek time with respect to disk I/O?
o What are monitors? How are they different from semaphores?*
o In the context of memory management, what are placement and
replacement algorithms?
o What is paging? What are demand- and pre-paging?*
o What is mounting?
o What do you mean by dispatch latency?
o What is multi-processing? What is multi-tasking? What is multithreading?
What is multi-programming?*
o What is compaction?
o What is memory-mapped I/O? How is it different frim I/O mapped I/O?
o List out some reasons for process termination.