Where does “شغال” come from?

شغال (Classical Persian) comes from Sanskrit सृगाल, from Proto-Indo-Aryan *śr̥gālás.

Ancestry of “شغال”, step by step

Step	Language	Word	Meaning
1	Sanskrit	सृगाल	jackal; a particular tree; name of a Vāsudeva
2	Proto-Indo-Aryan	*śr̥gālás	—