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1 #!/usr/bin/env perl
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2 use strict;
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3 use warnings;
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4 use Getopt::Std;
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5
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6 sub parse_command_line();
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7 sub build_regex_string();
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8 sub usage();
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9
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10 my $input_file ;
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11 my $output_file;
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12 my $find_pattern ;
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13 my $replace_pattern ;
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14 my $find_complete_words ;
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15 my $find_pattern_is_regex ;
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16 my $find_in_specific_column ;
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17 my $find_case_insensitive ;
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18 my $replace_global ;
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19 my $skip_first_line ;
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20
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21
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22 ##
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23 ## Program Start
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24 ##
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25 usage() if @ARGV<2;
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26 parse_command_line();
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27 my $regex_string = build_regex_string() ;
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28
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29 # Allow first line to pass without filtering?
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30 if ( $skip_first_line ) {
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31 my $line = <$input_file>;
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32 print $output_file $line ;
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33 }
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34
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35
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36 ##
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37 ## Main loop
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38 ##
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39
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40 ## I LOVE PERL (and hate it, at the same time...)
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41 ##
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42 ## So what's going on with the self-compiling perl code?
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43 ##
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44 ## 1. The program gets the find-pattern and the replace-pattern from the user (as strings).
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45 ## 2. If both the find-pattern and replace-pattern are simple strings (not regex),
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46 ## it would be possible to pre-compile a regex (with qr//) and use it in a 's///'
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47 ## 3. If the find-pattern is a regex but the replace-pattern is a simple text string (with out back-references)
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48 ## it is still possible to pre-compile the regex and use it in a 's///'
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49 ## However,
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50 ## 4. If the replace-pattern contains back-references, pre-compiling is not possible.
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51 ## (in perl, you can't precompile a substitute regex).
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52 ## See these examples:
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53 ## http://www.perlmonks.org/?node_id=84420
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54 ## http://stackoverflow.com/questions/125171/passing-a-regex-substitution-as-a-variable-in-perl
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55 ##
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56 ## The solution:
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57 ## we build the regex string as valid perl code (in 'build_regex()', stored in $regex_string ),
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58 ## Then eval() a new perl code that contains the substitution regex as inlined code.
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59 ## Gotta love perl!
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60
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61 my $perl_program ;
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62 if ( $find_in_specific_column ) {
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63 # Find & replace in specific column
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64
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65 $perl_program = <<EOF;
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66 while ( <STDIN> ) {
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67 chomp ;
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68 my \@columns = split ;
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69
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70 #not enough columns in this line - skip it
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71 next if ( \@columns < $find_in_specific_column ) ;
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72
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73 \$columns [ $find_in_specific_column - 1 ] =~ $regex_string ;
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74
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75 print STDOUT join("\t", \@columns), "\n" ;
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76 }
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77 EOF
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78
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79 } else {
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80 # Find & replace the entire line
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81 $perl_program = <<EOF;
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82 while ( <STDIN> ) {
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83 $regex_string ;
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84 print STDOUT;
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85 }
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86 EOF
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87 }
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88
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89
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90 # The dynamic perl code reads from STDIN and writes to STDOUT,
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91 # so connect these handles (if the user didn't specifiy input / output
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92 # file names, these might be already be STDIN/OUT, so the whole could be a no-op).
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93 *STDIN = $input_file ;
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94 *STDOUT = $output_file ;
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95 eval $perl_program ;
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96
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97
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98 ##
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99 ## Program end
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100 ##
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101
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102
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103 sub parse_command_line()
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104 {
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105 my %opts ;
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106 getopts('grsiwc:o:', \%opts) or die "$0: Invalid option specified\n";
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107
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108 die "$0: missing Find-Pattern argument\n" if (@ARGV==0);
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109 $find_pattern = $ARGV[0];
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110 die "$0: missing Replace-Pattern argument\n" if (@ARGV==1);
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111 $replace_pattern = $ARGV[1];
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112
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113 $find_complete_words = ( exists $opts{w} ) ;
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114 $find_case_insensitive = ( exists $opts{i} ) ;
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115 $skip_first_line = ( exists $opts{s} ) ;
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116 $find_pattern_is_regex = ( exists $opts{r} ) ;
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117 $replace_global = ( exists $opts{g} ) ;
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118
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119 # Search in specific column ?
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120 if ( defined $opts{c} ) {
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121 $find_in_specific_column = $opts{c};
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122
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123 die "$0: invalid column number ($find_in_specific_column).\n"
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124 unless $find_in_specific_column =~ /^\d+$/ ;
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125
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126 die "$0: invalid column number ($find_in_specific_column).\n"
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127 if $find_in_specific_column <= 0;
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128 }
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129 else {
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130 $find_in_specific_column = 0 ;
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131 }
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132
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133 # Output File specified (instead of STDOUT) ?
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134 if ( defined $opts{o} ) {
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135 my $filename = $opts{o};
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136 open $output_file, ">$filename" or die "$0: Failed to create output file '$filename': $!\n" ;
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137 } else {
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138 $output_file = *STDOUT ;
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139 }
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140
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141
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142 # Input file Specified (instead of STDIN) ?
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143 if ( @ARGV>2 ) {
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144 my $filename = $ARGV[2];
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145 open $input_file, "<$filename" or die "$0: Failed to open input file '$filename': $!\n" ;
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146 } else {
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147 $input_file = *STDIN;
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148 }
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149 }
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150
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151 sub build_regex_string()
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152 {
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153 my $find_string ;
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154 my $replace_string ;
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155
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156 if ( $find_pattern_is_regex ) {
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157 $find_string = $find_pattern ;
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158 $replace_string = $replace_pattern ;
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159 } else {
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160 $find_string = quotemeta $find_pattern ;
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161 $replace_string = quotemeta $replace_pattern;
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162 }
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163
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164 if ( $find_complete_words ) {
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165 $find_string = "\\b($find_string)\\b";
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166 }
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167
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168 my $regex_string = "s/$find_string/$replace_string/";
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169
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170 $regex_string .= "i" if ( $find_case_insensitive );
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171 $regex_string .= "g" if ( $replace_global ) ;
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172
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173
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174 return $regex_string;
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175 }
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176
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177 sub usage()
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178 {
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179 print <<EOF;
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180
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181 Find and Replace
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182 Copyright (C) 2009 - by A. Gordon ( gordon at cshl dot edu )
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183
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184 Usage: $0 [-o OUTPUT] [-g] [-r] [-w] [-i] [-c N] [-l] FIND-PATTERN REPLACE-PATTERN [INPUT-FILE]
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185
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186 -g - Global replace - replace all occurences in line/column.
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187 Default - replace just the first instance.
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188 -w - search for complete words (not partial sub-strings).
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189 -i - case insensitive search.
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190 -c N - check only column N, instead of entire line (line split by whitespace).
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191 -l - skip first line (don't replace anything in it)
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192 -r - FIND-PATTERN and REPLACE-PATTERN are perl regular expression,
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193 usable inside a 's///' statement.
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194 By default, they are used as verbatim text strings.
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195 -o OUT - specify output file (default = STDOUT).
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196 INPUT-FILE - (optional) read from file (default = from STDIN).
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197
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198
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199 EOF
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200
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201 exit;
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202 }
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