5.13.4 System Time management

5.13.4.1 date

The date program, for a normal user, displays current date and time. For an administrative user, date can
also set the system date and time. Refer to the date man page for more information. date generally
follows these steps:
1. Sets language.
2. Parses command-line arguments.
3. Validates command-line arguments.
4. If command line options indicate a system time set operation, invokes the stime() system call to
set the system time. The system call handler routine for stime() checks if the process possesses
the CAP_SYS_TIME capability. If it does, the operation is allowed; otherwise, an error is returned.
5. Processes returns from the stime() system call. Prints current time or error, depending on the
return value from the system call.
6. Exits.

5.13.4.2 hwclock

The hwclock command displays the current hardware clock time for a normal user. For an administrative
user, hwclock can also set the hardware clock time. It also allows the administrative user to set system time
from the hardware clock time. The hwclock man page gives more information. hwclock follows these
steps:
1. Sets language
2. Parses command-line arguments
3. Validates command-line arguments
4. If command-line options indicate a hardware clock set operation, then it opens the /dev/rtc device
special file, and performs I/O to set the value and kernel ensures that process has CAP_SYS_TIME
capability.
5. Or, if a user mentions uses the –directisa option, then hwclock uses explicit I/O instructions to
access CMOS memory registers, which sets the clock value. Here also the kernel ensures that process
has CAP_SYS_TIME capability.
6. If hwclock succeeds, it sets the value of hardware clock; otherwise, it gives the appropriate error
message.
7. Exits.
5.13.5 Other System Management

5.13.5.1 AMTU

Abstract machine test utility (AMTU): The TOE security functions are implemented using underlying
hardware. The TSF depends on the hardware to provide certain functionalities in order for the security
functions to work properly. Because the TOE includes different hardware architectures, a special tool is
provided to test features of the underlying hardware that the TSF depends on.
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