UPDATE(8)                                                            UPDATE(8)



NAME
       update - periodically update the super block

SYNOPSIS
       /etc/update

DESCRIPTION
       _U_p_d_a_t_e  is  a program that executes the _s_y_n_c(2) primitive every 30 sec‐
       onds.  This insures that the file system is fairly up to date  in  case
       of  a  crash.  This command should not be executed directly, but should
       be executed out of the initialization shell command file.

SEE ALSO
       sync(2), sync(8), init(8), rc(8)

BUGS
       With _u_p_d_a_t_e running, if the CPU is halted just as the _s_y_n_c is executed,
       a  file  system  can be damaged.  This is partially due to DEC hardware
       that writes zeros when NPR requests fail.   A  fix  would  be  to  have
       _s_y_n_c(8) temporarily increment the system time by at least 30 seconds to
       trigger the execution of _u_p_d_a_t_e_.  This would give 30 seconds  grace  to
       halt the CPU.



7th Edition                     April 27, 1985                       UPDATE(8)