alevt-date - display/set time received via Teletext
alevt-date displays the time received from a Teletext source. It can be used to set the system time. The date is not interpreted (not even transmitted on most channels). So it allows only adjustment of +/-12 hours. The default allowed adjustment is limited to +/-2 hours (use -delta to change). Without the -set option it just displays the date in the format of the date(1) command.
A summary of options is included below.
- Set system time from time received via Teletext.
- -delta seconds
- Maximum allowed adjustment made to the system time. The default is 7200 seconds (2 hours) and the maximum that may be given is 12 hours.
- -format string
- Format string to used to print the time. Look at strftime(3) for possible control sequences.
- -vbi device
- Use the given device name. Default: /dev/vbi, /dev/vbi0, /dev/video0, /dev/dvb/adapter0/demux0 tried in this order.
- -timeout seconds
- If the time can't be detected in seconds, the program is terminated with a SIGALRM.
- -progname name
- Specifies the program name if using the DVB interface.
- -pid pid
- Specifies the teletext PID if using the DVB interface.
- Show summary of options.
- Show version of program.
Before starting this program, you have to set the TV channel with another program like xawtv of set-tv.
Note: This program does not set the battery backed up clock of your computer. clock -w will do this.
The -progname or -pid option specifies the program or teletext PID if using the DVB interface.
If neither of these two options is used, alevt outputs informations about the currently accessible streams and uses the first of these PIDs as default. This output contains the PIDs and names that can be used as an input for the -progname or -pid option in the context of the currently chosen TV channel.
This program is just a toy. The time transmitted by the TV stations is more than inaccurate. Some are within a few seconds of your local time reference but others are more then 15 minutes off. You've been warned. (And don't assume the pkt8/30 time is better. It's even worse.)
Bug reports to <https://gitlab.com/alevt/alevt>.