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Sarkari MCQs Government Exam Question Bank
Question no. 91965

Which shell variable holds the process number for the current shell?

Select your answer for: Which shell variable holds the process number for the current shell?
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Answer: B. $$

Explanation

The double dollar sign shell variable expands to the process ID of the current shell. It provides scripts and users with a reliable way to reference their active process number. Shell interpreters evaluate this special parameter dynamically during execution time. Process IDs uniquely identify every running program instance within the operating system kernel. Special shell variables store contextual metadata regarding the current script or session. Scripting languages use internal process identifiers to manage temporary files and locks safely.

Shell scripts generate unique temporary filenames using the current process ID to prevent collisions. Debugging concurrent script executions often requires tracking process identifiers for log analysis. Advanced system automation relies on special shell variables to monitor execution environments. Option A is incorrect because dollar exclamation stores the process ID of background jobs. Option C is incorrect because zero holds the name of the shell script itself rather than its PID. Option D is incorrect because dollar asterisk expands to all positional parameters passed to a script.

Subject
Computer Science
Category
Software Engineering
Topic
—
Difficulty
medium

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