// install cronjob
pkg install cronie termux-services
// create your job using you text editor
crontab -e
// check crond (script which responsible for task scheduling) (firsttime)
pidof
// start contab for exicution
crond
// if you get error (this may happen when you start crond without providing any task or already you schedulled a job)
go to the file location given ion error and delet that file (crond.pid)