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1 # Filename: grep.py
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2 # Author: Ian N. Schenck
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3 # Version: 8/23/2005
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4 #
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5 # This script accepts regular expressions, as well as an "invert"
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6 # option, and applies the regular expression using grep. This wrapper
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7 # provides security and pipeline.
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8 #
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9 # Grep is launched based on these inputs:
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10 # -i Input file
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11 # -o Output file
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12 # -pattern RegEx pattern
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13 # -v true or false (output NON-matching lines)
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14
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15 import sys
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16 import os
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17 import re
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18 import string
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19 import commands
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20 from tempfile import NamedTemporaryFile
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21
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22 # This function is exceedingly useful, perhaps package for reuse?
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23 def getopts(argv):
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24 opts = {}
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25 while argv:
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26 if argv[0][0] == '-':
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27 opts[argv[0]] = argv[1]
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28 argv = argv[2:]
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29 else:
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30 argv = argv[1:]
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31 return opts
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32
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33 def main():
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34 args = sys.argv[1:]
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35
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36 try:
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37 opts = getopts(args)
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38 except IndexError:
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39 print "Usage:"
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40 print " -i Input file"
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41 print " -o Output file"
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42 print " -pattern RegEx pattern"
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43 print " -v true or false (Invert match)"
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44 return 0
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45
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46 outputfile = opts.get("-o")
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47 if outputfile == None:
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48 print "No output file specified."
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49 return -1
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50
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51 inputfile = opts.get("-i")
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52 if inputfile == None:
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53 print "No input file specified."
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54 return -2
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55
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56 invert = opts.get("-v")
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57 if invert == None:
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58 print "Match style (Invert or normal) not specified."
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59 return -3
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60
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61 pattern = opts.get("-pattern")
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62 if pattern == None:
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63 print "RegEx pattern not specified."
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64 return -4
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65
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66 # All inputs have been specified at this point, now validate.
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67
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68 # replace if input has been escaped, remove sq
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69 # characters that are allowed but need to be escaped
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70 mapped_chars = { '>' :'__gt__',
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71 '<' :'__lt__',
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72 '\'' :'__sq__',
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73 '"' :'__dq__',
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74 '[' :'__ob__',
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75 ']' :'__cb__',
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76 '{' :'__oc__',
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77 '}' :'__cc__'
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78 }
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79
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80 #with new sanitizing we only need to replace for single quote, but this needs to remain for backwards compatibility
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81 for key, value in mapped_chars.items():
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82 pattern = pattern.replace(value, key)
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83
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84 fileRegEx = re.compile("^[A-Za-z0-9./\-_]+$") #why?
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85 invertRegEx = re.compile("(true)|(false)") #why?
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86
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87 if not fileRegEx.match(outputfile):
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88 print "Illegal output filename."
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89 return -5
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90 if not fileRegEx.match(inputfile):
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91 print "Illegal input filename."
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92 return -6
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93 if not invertRegEx.match(invert):
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94 print "Illegal invert option."
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95 return -7
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96
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97 # invert grep search?
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98 if invert == "true":
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99 invertflag = " -v"
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100 print "Not matching pattern: %s" % pattern
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101 else:
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102 invertflag = ""
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103 print "Matching pattern: %s" % pattern
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104
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105 #Create temp file holding pattern
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106 #By using a file to hold the pattern, we don't have worry about sanitizing grep commandline and can include single quotes in pattern
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107 pattern_file_name = NamedTemporaryFile().name
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108 open( pattern_file_name, 'w' ).write( pattern )
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109
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110 #generate grep command
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111 commandline = "grep -E %s -f %s %s > %s" % ( invertflag, pattern_file_name, inputfile, outputfile )
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112
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113 #run grep
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114 errorcode, stdout = commands.getstatusoutput(commandline)
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115
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116 #remove temp pattern file
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117 os.unlink( pattern_file_name )
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118
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119 #return error code
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120 return errorcode
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121
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122 if __name__ == "__main__":
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123 main()
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