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perl -n -e "print qq/$.:\t$_\n/;" textfile.txt
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while ( <> ) {
.......... # Your code goes here.
print $_;
}
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perl -pe "s/\bperl\b/Perl/g;" textfile.txt
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perl -pe "s/\bperl\b/Perl/g;" textfile.txt >temptext.txt
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perl -pi.bak -e "s/\bperl\b/Perl/g" infile.txt