| #! /usr/bin/env python |
| |
| """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, msg: |
| usage("error in regular expression: %s" % str(msg)) |
| try: |
| f = open(filename) |
| except IOError, msg: |
| usage("can't open %s: %s" % (repr(filename), str(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 |
| lines.reverse() |
| for line in 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() |
