Implement a "slow-motion" Unix 'cat' command.

slowcat.py

#!/usr/bin/env python

"""
Implement a "slow-motion" Unix 'cat' command.

Intended to be used with tools like 'asciinema', see asciinema.org.
None of the options of Unix 'cat' are implemented here.

Examples:

    slocat.py slocat.py --pause 0.1
    echo -e "abc\nbbbb" | slocat.py - --pause 0.1
    tree . | slocat.py - --pause 0.1
"""

from __future__ import print_function
import sys
import time
import argparse

DELAY = 0.1

__author__  = "Dinu Gherman"
__date__    = "2017-07-28"
__license__ = "GLP 3"
__version__ = "0.1"

def slow_cat(path, pause=DELAY):
    """
    Output text file line by line, but with a short delay after each line.
    """
    with sys.stdin if path == '-' else open(path) as f:
        for line in f.readlines():
            print(line.rstrip())
            time.sleep(pause)

def _main():
    """
    Command-line interface"
    """
    desc = "Output lines of a file like with Unix 'cat', but in slow-motion."
    parser = argparse.ArgumentParser(description=desc)
    parser.add_argument("path", nargs='+', help="Path of some text file.")
    parser.add_argument("--pause", metavar="PERIOD", default=DELAY,
        type=float, help='Delay in seconds (default: %f).' % DELAY)
    opts = parser.parse_args()
    for path in opts.path:
        slow_cat(path, opts.pause)

if __name__ == "__main__":
    _main()