quote_line_by_offset.py

#!/usr/bin/env python3

"""
Quote stdin line containing the Nth character, in absolute offset,
counting each newline as a character too.

Inspired by https://stackoverflow.com/a/79399803/531179

In the name José João in this file, accents are on offsets +210 and on +214.
"""

from argparse import ArgumentParser
import sys

if __name__ == "__main__":
    argP = ArgumentParser()
    argP.add_argument('ABSOLUTE_OFFSET', type=int, help="which character")
    argP.add_argument('FILE', nargs='?', type=lambda fp: open(fp), default=sys.stdin, help="optional file path")
    opts = argP.parse_args()
    #print(opts)
    n = opts.ABSOLUTE_OFFSET
    lineno = 1
    for line in opts.FILE.readlines():
        if len(line) > n:
            # found, print out
            print(f"{lineno}: {line}")
            charp = len(str(lineno)) + 2 + n
            caret = '-' * charp + '^'
            print(caret)
            break
        lineno += 1
        n -= len(line)