| 1 | n/a | #! /usr/bin/env python3 |
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| 2 | n/a | |
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| 3 | n/a | """Reverse grep. |
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| 4 | n/a | |
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| 5 | n/a | Usage: rgrep [-i] pattern file |
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| 6 | n/a | """ |
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| 7 | n/a | |
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| 8 | n/a | import sys |
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| 9 | n/a | import re |
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| 10 | n/a | import getopt |
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| 11 | n/a | |
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| 12 | n/a | |
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| 13 | n/a | def main(): |
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| 14 | n/a | bufsize = 64 * 1024 |
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| 15 | n/a | reflags = 0 |
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| 16 | n/a | opts, args = getopt.getopt(sys.argv[1:], "i") |
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| 17 | n/a | for o, a in opts: |
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| 18 | n/a | if o == '-i': |
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| 19 | n/a | reflags = reflags | re.IGNORECASE |
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| 20 | n/a | if len(args) < 2: |
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| 21 | n/a | usage("not enough arguments") |
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| 22 | n/a | if len(args) > 2: |
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| 23 | n/a | usage("exactly one file argument required") |
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| 24 | n/a | pattern, filename = args |
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| 25 | n/a | try: |
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| 26 | n/a | prog = re.compile(pattern, reflags) |
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| 27 | n/a | except re.error as msg: |
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| 28 | n/a | usage("error in regular expression: %s" % msg) |
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| 29 | n/a | try: |
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| 30 | n/a | f = open(filename) |
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| 31 | n/a | except IOError as msg: |
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| 32 | n/a | usage("can't open %r: %s" % (filename, msg), 1) |
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| 33 | n/a | f.seek(0, 2) |
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| 34 | n/a | pos = f.tell() |
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| 35 | n/a | leftover = None |
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| 36 | n/a | while pos > 0: |
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| 37 | n/a | size = min(pos, bufsize) |
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| 38 | n/a | pos = pos - size |
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| 39 | n/a | f.seek(pos) |
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| 40 | n/a | buffer = f.read(size) |
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| 41 | n/a | lines = buffer.split("\n") |
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| 42 | n/a | del buffer |
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| 43 | n/a | if leftover is None: |
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| 44 | n/a | if not lines[-1]: |
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| 45 | n/a | del lines[-1] |
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| 46 | n/a | else: |
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| 47 | n/a | lines[-1] = lines[-1] + leftover |
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| 48 | n/a | if pos > 0: |
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| 49 | n/a | leftover = lines[0] |
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| 50 | n/a | del lines[0] |
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| 51 | n/a | else: |
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| 52 | n/a | leftover = None |
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| 53 | n/a | for line in reversed(lines): |
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| 54 | n/a | if prog.search(line): |
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| 55 | n/a | print(line) |
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| 56 | n/a | |
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| 57 | n/a | |
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| 58 | n/a | def usage(msg, code=2): |
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| 59 | n/a | sys.stdout = sys.stderr |
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| 60 | n/a | print(msg) |
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| 61 | n/a | print(__doc__) |
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| 62 | n/a | sys.exit(code) |
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| 63 | n/a | |
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| 64 | n/a | |
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| 65 | n/a | if __name__ == '__main__': |
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| 66 | n/a | main() |
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