33 lines
860 B
Bash
33 lines
860 B
Bash
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#!/bin/sh
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# This shell scripts reads the offset from the file and sets the 'swclock'.
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#
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# To keep the offset calculation simple, the epoch timestamp is used.
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#
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# The RTC is read from the sysfs node.
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#
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# To set the system time, command "date" is used. The "@" sign marks an
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# epoch time format. As the "date" command offers no quiet option, the
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# output is written to the null device.
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rtc_sys_node="/sys/class/rtc/rtc0/since_epoch"
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offset_file="/var/cache/swclock-offset/offset-storage"
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# check presence of rtc sys node
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if [ ! -f $rtc_sys_node ]; then
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exit 1
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fi
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# check presence of offset file
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if [ ! -f $offset_file ]; then
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exit 2
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fi
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# calculate system time
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hwclock_epoch=$(cat $rtc_sys_node)
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offset_epoch=$(cat $offset_file)
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swclock_epoch=$((hwclock_epoch + offset_epoch))
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# set system time, dump output
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date --utc --set=@$swclock_epoch > /dev/null
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