GPSLOGNTP(1) GPSD Documentation GPSLOGNTP(1)

gpslogntp - log gpsd data for ntpviz

gpslogntp [-h] [-l LOGFILE] [-o] [-w WAIT] [-v] [-V]
-h, --help            show this help message and exit
-l LOGFILE, --logfile LOGFILE
                      append log data to LOGFILE instead of stdout
-o, --once            log one line, then exit
-w WAIT, --wait WAIT  wait WAIT seconds between log lines, default 5
-v, --verbose         be verbose
-V, --version         show program's version number and exit

gpslogntp connects to a local gpsd daemon and logs the number of satellites in use and the Time Dilution of Precision (TDOP). gpslogntp can run as any user, no special privileges are required. This log is intended to be used by ntpviz.

The default is to write the data to stdout about once every 5 seconds. The log file looks like:

# Time       Device     TDOP     nSat
1483668619.0 /dev/ttyS0 0.820000 7
1483668624.0 /dev/ttyS0 0.820000 7
1483668629.0 /dev/ttyS0 0.820000 7

Time is the POSIX time of when the log line is written.

Device is the GPS device the data came from.

TDOP is the Time Dilution of Precision as reported by the GPS. Some GPS always output a static TDOP.

nSat is the number of satellites in use.

Formerly known as ntploggps and formerly part of NTPsec.

Note: Many GNSS receivers always report TDOP as "1.0".

-h, --help

Displays usage information and exits.

-l LOGFILE, --logfile LOGFILE

Append log data to LOGFILE instead of stdout

-o, --once

Log one line, then exit.

-v, --verbose

Be verbose

-w WAIT, --wait WAIT

Wait WAIT seconds after each log line. The default is 5 seconds. This is just the minimum wait time. gpsd may be reporting data at a much slower interval.

-V, --version

show program’s version number and exit

gpslogntp

This the simplest use of this program. It can be used to check the status of the local gpsd daemon.

gpslogntp -l /var/log/ntpstats/gpsd -w 60 &

This will continuously log the gpsd data in the background to the file /var/log/ntpstats/gpsd. Only log every 60 seconds.

Gary E. Miller

One of the following exit values will be returned:

0 (EXIT_SUCCESS)

Successful program execution.

1 (EXIT_FAILURE)

The operation failed or the command syntax was not valid.

gpsd(8), gps(1), ntpviz(1), ntpd(8).

Project web site: https://gpsd.io/

This file is Copyright by the GPSD project
This file is Copyright by the NTPSec project
SPDX-License-Identifier: BSD-2-clause

Gary E. Miller

2025-05-06 GPSD, Version 3.26