In some cases you can check whether the standard file handles (e.g. STDIN) are connected to a tty:

$ perl -E 'say -t STDIN ? "interactive":"non-interactive"'
interactive
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In other cases, you might want to investigate what the parent process' command line was:

perl -E 'open F, "/proc/".getppid()."/cmdline" or die $!; $_=<F>; tr/\
+0/ /; say'
bash -rcfile .bashrc
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