sending and getting data from node MCU to php page

hi everyone
i have worked on this project :
this video
i improved this project to make it login with several esp and that worked , but i want to know from witch esp the fingerprint has taken, so i send a special character and check if it is the same character then it will display it

i have send a string “first” in line 126 in nodeMCU esp 12-E but how can i get that string first in getdata.php file and then show it in user_log_up.php

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