Program 1 CS 344: This Assignment Asks You To Write A Bash S

Program 1 Cs 344this Assignment Asks You To Write A Bash Shell Scrip

This assignment requires you to write a Bash shell script named stats that computes statistical measures—specifically averages and medians—from input data. The script is designed to help you become proficient with Unix shell scripting, utilities, process management, and signal handling. It must support calculations across either rows or columns of a tab-separated data file, or via standard input if no file is provided.

The key features include argument validation, flexibility with input sources, calculation accuracy, temporary file management, rounding rules, and error handling. The script will accept command options -rows or -cols (with abbreviations like -r or -c), and an optional filename. All error messages should be directed to standard error, and the computed statistics to standard output. Success should return an exit code of 0; failure, 1.

The script must perform argument validation, check for file readability, handle signals for cleanup, and perform computations entirely within Bash using commands like read, expr, cut, head, tail, wc, and sort. Calculations are to be based on whole numbers, with averages rounded half up, and median calculated accordingly. The script must generate a temporary file with the process ID in its name and ensure its removal upon completion or interruption.

Paper For Above instruction

The task of creating a Bash script named stats that computes averages and medians from tab-delimited numerical data is both intricate and instructive. This assignment guides the development of essential Bash scripting skills, including argument parsing, file handling, process management, and numeric computations within a shell environment, which are fundamental for system scripting and automation.

At its core, the stats script must accept a command option indicating whether calculations are to be performed across rows or columns. It also accommodates an optional filename argument; if omitted, data is read from standard input. This flexibility necessitates rigorous argument validation, including recognizing abbreviations such as -r or -c for rows and columns, respectively, and handling invalid inputs gracefully with error messages sent to standard error.

In terms of processing, the script must handle tab-separated files where each line contains an equal number of integer values. For row-wise calculations, data is processed line-by-line; for column-wise operations, data must be transposed or aggregated across lines. The utility commands read, cut, head, tail, and sort are critical in reading and manipulating data efficiently.

Calculations of mean involve summing the relevant data and dividing by the count, using expr for whole-number integer operations. The mean must be rounded half up, which involves inspecting the fractional part and adjusting accordingly. Median calculation is more complex, requiring data sorting and selection of the middle value, with special handling for even-sized data sets where the larger middle value is chosen.

Temporary files serve an essential role in processing, particularly for storing sorted data during median calculation. These files should be named with the script's process ID and cleaned up after execution, employing the trap command to handle signals such as INT, HUP, and TERM, ensuring cleanup even if the script is interrupted unexpectedly.

Robust error handling includes verifying the existence and readability of input files, checking argument counts and formats, and providing clear messages. The script should return exit status 0 upon success and 1 on failure, enabling integration with other system scripts or commands.

The overall implementation demands careful consideration of shell scripting best practices, including adequate commenting, organized code structure, and clear variable naming, to facilitate readability and maintainability. Using only Bash scripting commands, the complexity of reading, processing, and computing large data sets is notable, but manageable through command pipelines and control structures.

In conclusion, this script exemplifies practical application of shell scripting to automate statistical calculations in UNIX-based environments. Its development enhances understanding of process control, file management, data parsing, and numeric computation within Bash, preparing students for more sophisticated scripting and system management tasks.

References

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• Wilkinson, K. (2014). Bash Shell Scripting Tutorial. TutorialsPoint. Available at: https://www.tutorialspoint.com/unix/shell_scripting.htm