IIRC the -e switch means eval, and IMHO you cant use __DATA__ in eval.

The second form you showed is completely different since you are using a shell (bash?) here-doc which is similar to execute a file.

Anyway there is no big point in using __DATA__ within -e'...' since the shell offers plenty of possibilities to pipe the data into your snippet.

for instance

perl -e'print <>' <<XXX
> 1
> 2
> 3
> XXX
1
2
3
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