print-contecnt-cli.py

from argparse import ArgumentParser
import sys

def create_parser():
    parser = ArgumentParser(description="Utility to print content of specific line number from a given file.")
    parser.add_argument('filename', help='File Name')
    parser.add_argument('--line', '-l', type=int, required=True, help='Line number in given file')
    return parser

def print_contents(filename, line):
    if line <= 0:
        print(f"Line can't be negative or zero.")
        sys.exit(1)
    lines = []
    try:
        with open(filename, 'r') as f:
            lines = f.readlines()
    except OSError as err:
        print(f"Error: {err}")
        sys.exit(1)
    if line > len(lines):
        print(f"File is too short. Line {line} doesn't exists in the file. Line number should be between 1 to {len(lines)}.")
        sys.exit(1)
    return lines[line -1]
    print(f"Contents of line {line} in {filename}:\n{lines[line -1]}")

def main():
    parser = create_parser()
    args = parser.parse_args()
    line = print_contents(args.filename.strip(),args.line)
    print(f"Contents of line {args.line} in {args.filename.strip()}:\n{line}")

if __name__ == "__main__":
    main()

"""
Sample Run:
~ $ python3.9 print-content.py names.txt -l 3
Contents of line 3 in names.txt:
Arnold

~ $ python3.9 print-content.py names.txt -l 32
File is too short. Line 32 doesn't exists in the file. Line number should be between 1 to 9.
~ $ python3.9 print-content.py names.txt -l -2
Line can't be negative or zero.
~ $
"""