tr/// is the most efficient for a simple mapping, for example rot-13 is 

perl -pe'tr/a-zA-Z/n-za-mN-ZA-M/' file

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or in a script 
$line =~ tr/a-zA-Z/n-za-mN-ZA-M/;

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Update: fixed typo, changed A-m to A-M

In reply to Re: Text String Jumble by hipowls
in thread Text String Jumble by Anonymous Monk

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