run_scripts()
mkinitramfs automatically add ORDER file in folders like init-top, local-premount, which run the scripts in the folder in order.
the order is determined by analysis the output of prereqs() function in all boot scripts. see
this anotation
No guarantees are made as to the order in which the different scripts are executed unless the prereqs are setup in the script. Please notice that PREREQ is only honored inside a single directory. So first the scripts in /usr/share/initramfs-tools are ordered according to their PREREQ values and executed. Then all scripts in /etc/initramfs-tools are ordered according to their PREREQ values and executed.
PREREQ is used to determine the execution order of hook scripts