Apenas no caso de alguém preferir uma alternativa em Python:
#!/usr/bin/env python2
# -*- encoding: ascii -*-
"""tail.py"""
import sys
import argparse
import time
import re
# Create a command-line parser
parser = argparse.ArgumentParser()
parser.add_argument(
"-f", "--input-file",
help="File to search through.",
dest="input_file", type=str,
)
parser.add_argument(
"-p", "--pattern",
help="Regular expression to match.",
default=r'.*',
dest="pattern", type=str,
)
parser.add_argument(
"-m", "--match-limit",
help="Number of matches before exiting.",
default=float(1),
dest="match_limit", type=int,
)
parser.add_argument(
"-q", "--quiet",
help="Don't print matched lines.",
default=False,
dest="quiet", type=bool,
)
# Define the file-watching function
def watch_for_matches(file_handle, pattern, match_limit, quiet):
# Count the number of matched lines
matches_found = 0
# Get the next line
line = file_handle.readline()
# Check to see if the limit has been reached
while(matches_found < match_limit):
# Match the line against the given regular expression
if(line and re.search(pattern, line)):
# Optionally print the matched line
if not quiet:
sys.stdout.write(line)
# Increment the match counter
matches_found += 1
# Optionally wait for a moment
time.sleep(0.25)
# Get the next line of input
line = file_handle.readline()
# If the match limit is reached, exit with an error
sys.exit(1)
# Parse the command-line arguments
args = parser.parse_args()
# Execute the function
if args.input_file:
with open(args.input_file, 'r') as file_handle:
watch_for_matches(file_handle, args.pattern, args.match_limit, args.quiet)
# If no file is given, use standard input instead
else:
watch_for_matches(sys.stdin, args.pattern, args.match_limit, args.quiet)