Basics in Unix System : Practice MCQ Questions & Answers with Explanations

The /etc directory in Linux contains all system-wide configuration files, including the /etc/passwd and /etc/shadow files for user authentication.

EXT3 (Third Extended Filesystem) is a native file system specifically designed and widely used for Linux partitions.

The chmod -R a+x progs command recursively (-R) adds (+) execute (x) permissions for all (a) users to the 'progs' directory and its contents.

UNIX fundamentally provides three file permissions: Read, Write, and Execute. These can be modified using the chmod command.

Windows CreateProcess() corresponds functionally to the UNIX fork() and exec(), WaitForSingleObject() maps to wait(), ReadFile() to read(), and CloseHandle() to close().

The nice command executes a program with a specified scheduling priority, effectively setting the task priority in UNIX.

The JMP (unconditional jump) instruction changes the instruction pointer but does not perform an arithmetic or logical operation, so no status flags are affected.

The Kernel is the core component of the operating system that resides between the hardware and the system call interface, managing system resources.

Linux fundamentally uses a Completely Fair Scheduler (CFS), which is a type of fair preemptive scheduling to allocate CPU time to processes.

In standard UNIX shells, the test command uses the = operator to compare strings for equality, though -eq is sometimes incorrectly conflated with string comparison despite being strictly for integers.

The UNIX file system utilizes a hierarchical directory structure, organizing files and directories into a tree-like hierarchy starting from the root (/).

Process 0 is typically the sched or swapper process, while Process 1 is the init process. Therefore, stating that Process 0 is the init process is incorrect.

The special variable $! holds the process ID of the most recently executed background pipeline, which would be the sleep command in this case.

The grep command with -v inverts the search to output lines that do not match the pattern, while -n includes the line numbers.

Scheduling parameters (like priority and recent CPU usage) are kept in the process table (proc structure) because they must be accessible even when the process is swapped out, unlike the user structure.

UNIX supports multiple file types, primarily regular files, directories, and special (device) files, adhering to its "everything is a file" philosophy.

UNIX system calls provide direct interfaces to the kernel: exec() replaces the process image, brk() changes the data segment space allocation, wait() pauses execution until a child finishes, and fork() spawns a new process.

WOW32 (Windows on Windows 32-bit) is a subsystem that allows older 16-bit Windows applications to run seamlessly on 32-bit Windows operating systems.

When multiple files are opened in vi, they are loaded into the buffer array, and 'ex' commands like :n (next) can be used to switch between them.

The Super block contains critical metadata about the file system, including the size, status, and a list of free disk blocks.