How does react native run a certain program every time it opens app?

rn needs to execute a function to read data from the pasteboard every time app is opened, but there seems to be no such function in the life cycle, either once or only if the state of the component changes. How should I do this?

Feb.27,2021

write a global function

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b309ed-2bd36.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b309ed-2bd36.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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