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