Use busybox crond, crontab on Android

1. Download busybox binary or compile busybox to get busybox
   
   
2. push busybox to android device
   # ./adb push busybox /data/busybox
   
   
3. create /etc/passwd /etc/group /etc/shadow
   (android shell) # cd /data
   (android shell) # touch passwd
   (android shell) # touch group
   (android shell) # touch shadow
   (android recovery mode) # ln -s /data/passwd /system/etc/passwd
   (android recovery mode) # ln -s /data/group /system/etc/group
   (android recovery mode) # ln -s /data/shadow /system/etc/shadow
   
   
4. create Symbolic linker /bin/sh /bin/vi
   (android shell) # mount -o remount,rw rootfs /
   (android shell) # mkdir /bin
   (android shell) # ln -s /system/bin/sh
   (android shell) # ln -s /system/xbin/vi
   
   
5. create folder /var/spool/cron/crontabs
   (android shell) # mkdir /var
   (android shell) # mkdir /var/spool
   (android shell) # mkdir /var/spool/cron
   (android shell) # mkdir /var/spool/cron/crontabs
   
   
6. create file root (crontab)
   you can use vi or ./busybox crontab -e to create file
   (android shell) # vi /var/spool/cron/crontabs/root
   (android shell) # ./busybox crontab -e
   file format
   M H d m w CMD
   * * * * * command
7. run crond
   (android shell) # ./busybox crond -l 0 -L /data/cron.log