Shell literal

-MB';$'F=shift
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produces the arg

-MB;$F=shift
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You're probably familiar with -M. It used to load a module. It does so by inserting

use MODULENAME;
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into the source. In this case, MODULENAME is B;$F=shift, so

use B;$F=shift;
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is inserted into the source. B is a core module. It's not being used at all by the program. The only purpose to load it is to execute $F=shift; before the -n loop with very few keystrokes. The following would also work; it's just not nearly as short:

'-MData::Dumper; $F=shift'
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