Well, that's exactly what tr does.

Example: 

perl -le '$line1 = "asdadAADSAsdfsfASASDjljsdASDAS"; $line1 =~ tr/[A-Z
+a-z]/[a-zA-Z]/;print $line1;'

[download]
Prints: 
ASDADaadsaSDFSFasasdJLJSDasdas

[download]

In reply to Re^3: uppercase/lowercase in a single expression by McDarren
in thread uppercase/lowercase in a single expression by greatshots

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