You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
67 lines
1.5 KiB
67 lines
1.5 KiB
4 years ago
|
#! /usr/bin/env python3
|
||
|
|
|
||
|
|
"""Reverse grep.
|
||
|
|
|
||
|
|
Usage: rgrep [-i] pattern file
|
||
|
|
"""
|
||
|
|
|
||
|
|
import sys
|
||
|
|
import re
|
||
|
|
import getopt
|
||
|
|
|
||
|
|
|
||
|
|
def main():
|
||
|
|
bufsize = 64 * 1024
|
||
|
|
reflags = 0
|
||
|
|
opts, args = getopt.getopt(sys.argv[1:], "i")
|
||
|
|
for o, a in opts:
|
||
|
|
if o == '-i':
|
||
|
|
reflags = reflags | re.IGNORECASE
|
||
|
|
if len(args) < 2:
|
||
|
|
usage("not enough arguments")
|
||
|
|
if len(args) > 2:
|
||
|
|
usage("exactly one file argument required")
|
||
|
|
pattern, filename = args
|
||
|
|
try:
|
||
|
|
prog = re.compile(pattern, reflags)
|
||
|
|
except re.error as msg:
|
||
|
|
usage("error in regular expression: %s" % msg)
|
||
|
|
try:
|
||
|
|
f = open(filename)
|
||
|
|
except IOError as msg:
|
||
|
|
usage("can't open %r: %s" % (filename, msg), 1)
|
||
|
|
f.seek(0, 2)
|
||
|
|
pos = f.tell()
|
||
|
|
leftover = None
|
||
|
|
while pos > 0:
|
||
|
|
size = min(pos, bufsize)
|
||
|
|
pos = pos - size
|
||
|
|
f.seek(pos)
|
||
|
|
buffer = f.read(size)
|
||
|
|
lines = buffer.split("\n")
|
||
|
|
del buffer
|
||
|
|
if leftover is None:
|
||
|
|
if not lines[-1]:
|
||
|
|
del lines[-1]
|
||
|
|
else:
|
||
|
|
lines[-1] = lines[-1] + leftover
|
||
|
|
if pos > 0:
|
||
|
|
leftover = lines[0]
|
||
|
|
del lines[0]
|
||
|
|
else:
|
||
|
|
leftover = None
|
||
|
|
for line in reversed(lines):
|
||
|
|
if prog.search(line):
|
||
|
|
print(line)
|
||
|
|
|
||
|
|
|
||
|
|
def usage(msg, code=2):
|
||
|
|
sys.stdout = sys.stderr
|
||
|
|
print(msg)
|
||
|
|
print(__doc__)
|
||
|
|
sys.exit(code)
|
||
|
|
|
||
|
|
|
||
|
|
if __name__ == '__main__':
|
||
|
|
main()
|