How does the kernel differentiate device files and ordinary files?

Unix Interview Questions

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97. How does the kernel differentiate device files and ordinary files?

Kernel checks 'type' field in the file's inode structure.

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Other Interview Questions

• How are devices represented in UNIX?
• What is 'inode'?
• Brief about the directory representation in UNIX
• What are the Unix system calls for I/O?
• How do you change File Access Permissions?
• What are links and symbolic links in UNIX file system?
• What is a FIFO?
• How do you create special files like named pipes and device files?
• Discuss the mount and unmount system calls
• How does the inode map to data block of a file?
• What is a shell?
• Brief about the initial process sequence while the system boots up.
• What are various IDs associated with a process?
• Explain fork() system call.
• Predict the output of the following program code
• Predict the output of the following program code
• List the system calls used for process management:
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• How can a parent and child process communicate?
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• What are the process states in Unix?
• What Happens when you execute a program?
• What Happens when you execute a command?
• What is a Daemon?
• What is 'ps' command for?
• How would you kill a process?
• What is an advantage of executing a process in background?
• How do you execute one program from within another?
• What is IPC? What are the various schemes available?
• What is the difference between Swapping and Paging?
• What is major difference between the Historic Unix and the new BSD release of Unix System V in terms of Memory Management?
• What is the main goal of the Memory Management?
• What is a Map?
• What scheme does the Kernel in Unix System V follow while choosing a swap device among the multiple swap devices?
• What is a Region?
• What are the events done by the Kernel after a process is being swapped out from the main memory?
• Is the Process before and after the swap are the same? Give reason.
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• What are the entities that are swapped out of the main memory while swapping the process out of the main memory?
• What is Fork swap?
• What is Expansion swap?
• How the Swapper works?
• What are the processes that are not bothered by the swapper? Give Reason.
• What are the requirements for a swapper to work?
• What are the criteria for choosing a process for swapping into memory from the swap device?
• What are the criteria for choosing a process for swapping out of the memory to the swap device?
• What do you mean by nice value?
• What are conditions on which deadlock can occur while swapping the processes?
• What are conditions for a machine to support Demand Paging?
• What is ‘the principle of locality’?
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• What is the window of the working set of a process?
• What is called a page fault?
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• What are the bits that support the demand paging?
• How the Kernel handles the fork() system call in traditional Unix and in the System V Unix, while swapping?
• Difference between the fork() and vfork() system call?
• What is BSS(Block Started by Symbol)?
• What is Page-Stealer process?
• Name two paging states for a page in memory?
• What are the phases of swapping a page from the memory?
• What is page fault? Its types?
• In what way the Fault Handlers and the Interrupt handlers are different?
• What is validity fault?
• What does the swapping system do if it identifies the illegal page for swapping?
• What are states that the page can be in, after causing a page fault?
• In what way the validity fault handler concludes?
• At what mode the fault handler executes?
• What do you mean by the protection fault?
• How the Kernel handles the copy on write bit of a page, when the bit is set?
• For which kind of fault the page is checked first?
• In what way the protection fault handler concludes?
• How the Kernel handles both the page stealer and the fault handler?
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• 74. What is ex and vi ?
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• Write a command to display a file’s contents in various formats?
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• Is it possible to count number char, line in a file; if so, How?
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• What is redirection?
• How to terminate a process which is running and the specialty on command kill 0?
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• Explain kill() and its possible return values.