### Setup pkgin and Install Tools on NetBSD

Source: https://gpsd.io/building.html

Configures pkgin and installs necessary tools like Python 3.7, curses, scons, and git on NetBSD 8.1.

```bash
# export PKG_PATH=\"http://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/amd64/8.1/All\"
# pkg_add -v pkgin
# echo http://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/amd64/8.1/All > \
   /usr/pkg/etc/pkgin/repositories.conf
# pkgin update
# pkgin install python37 py37-curses
# ln -s /usr/pkg/bin/python3.7 /usr/pkg/bin/python
# ln -s /usr/pkg/bin/python3.7 /usr/pkg/bin/python3
# pkgin install py37-scons
# pkgin install ncurses
# pkgin install openssl mozilla-rootcerts
# mozilla-rootcerts install
# pkgin install git
```

--------------------------------

### Start GPSD and chrony Services

Source: https://gpsd.io/gpsd-time-service-howto.html

This sequence demonstrates the preferred procedure for starting chronyd and gpsd when running as root, ensuring services are ready before the other. It includes killing existing processes, starting chronyd, waiting briefly, starting gpsd, and then checking the connection with cgps.

```shell
$ su -
# killall -9 gpsd chronyd
# chronyd -f /etc/chrony/chrony.conf
# sleep 2
# gpsd -n /dev/ttyXX
# sleep 2
# cgps
```

--------------------------------

### Build and Install gpsd on Gentoo

Source: https://gpsd.io/building.html

Clones the gpsd source, cleans the build tree, builds the project, checks the results, and installs it. Ensure prerequisites are installed before running.

```bash
# make a place to keep the source
mkdir -p /usr/local/src/GPSD
cd /usr/local/src/GPSD

# grab a shallow clone of gpsd from git.
git clone --depth 1 https://gitlab.com/gpsd/gpsd.git
cd gpsd

# clean the tree, just in case
scons -c

# build the project
scons

# check the results
scons check

# and install if it looks good
scons install
```

--------------------------------

### Install Documentation Build Tool on Ubuntu

Source: https://gpsd.io/building.html

Installs asciidoctor, a tool required for building the project's documentation.

```bash
apt install asciidoctor
```

--------------------------------

### Install Build Tools on OpenBSD

Source: https://gpsd.io/building.html

Installs scons and git on OpenBSD 6.6 and 7.x, and creates a Python symlink.

```bash
# syspatch -c
# syspatch
# pkg_add -u
# pkg_add scons
# pkg_add git
# ln -s /usr/local/bin/python2 /usr/local/bin/python
```

--------------------------------

### Install scons and git on FreeBSD

Source: https://gpsd.io/building.html

Installs scons for building and git for source control on FreeBSD systems.

```bash
# pkg install scons
# pkg install git
```

--------------------------------

### Start ptp4l Daemon with Hardware Timestamping

Source: https://gpsd.io/gpsd-time-service-howto.html

Start the ptp4l daemon on the slave server with hardware timestamping enabled.

```bash
# ethtool --set-eee eth0 eee off
# ptp4l -H -f /usr/local/etc/ptp4l.conf &
# sleep 3
```

--------------------------------

### VERSION Object Example

Source: https://gpsd.io/gpsd_json.html

Example of a version response from the gpsd daemon. This is sent to clients upon connection.

```json
{"class":"VERSION","version":"2.40dev",
    "rev":"06f62e14eae9886cde907dae61c124c53eb1101f",
    "proto_major":3,"proto_minor":1
}
```

--------------------------------

### Install Build Dependencies on Ubuntu

Source: https://gpsd.io/building.html

Installs essential development tools and libraries required for building gpsd on Ubuntu.

```bash
apt install gcc scons python-gi python-gi-cairo g++
apt install libncurses5-dev libtinfo-dev  pps-tools
apt install gir1.2-gtk-3.0
```

--------------------------------

### RMB Example

Source: https://gpsd.io/NMEA.html

An example of a complete $GPRMB sentence, illustrating typical values for navigation data.

```text
$GPRMB,A,0.66,L,003,004,4917.24,N,12309.57,W,001.3,052.5,000.5,V*0B
```

--------------------------------

### ubxtool Examples

Source: https://gpsd.io/index.html

Examples for performing common `ubxtool` tasks. `ubxtool` is a utility for interacting with u-blox GPS receivers.

```bash
# Example: Read configuration from a u-blox device
# ubxtool -p /dev/ttyACM0 --cfg-get

# Example: Set the baud rate of a u-blox device
# ubxtool -p /dev/ttyACM0 --cfg-set CFG-PRT-BAUD 9600

# Example: Poll for current GPS time
# ubxtool -p /dev/ttyACM0 --poll TIME-UTC

# Example: Read NMEA sentences
# ubxtool -p /dev/ttyACM0 --nmea

```

--------------------------------

### Main Function Entry Point

Source: https://gpsd.io/gpsd-client-example-code.html

The main function for the gpsd client example. This example does not handle command-line options for clarity.

```c
int main(int argc, char *argv[])
{


```

--------------------------------

### TOFF Message Example

Source: https://gpsd.io/gpsd_json.html

An example of the TOFF JSON message, which reports the offset between the host's clock and GPS time at the start of a cycle.

```json
{"class":"TOFF","device":"/dev/ttyUSB0",
     "real_sec":1330212592, "real_nsec":343182,
     "clock_sec":1330212592,"clock_nsec":343184,
     "precision":-2}
```

--------------------------------

### Release Readiness State Announcement Example

Source: https://gpsd.io/hacking.html

An example of how to announce release state changes on the developer list, including the status of different device types and the expected release date.

```text
Red light: total breakage in Garmin USB, partial breakage in Garmin serial
Blue light: no known blockers, cosmetic problems in xgps
Yellow light: Garmins tested successfully 20 Dec 2007
Green light: I'm expecting to call freeze in about 10 days
Freeze: Scheduled release date 1 Feb 2008
```

--------------------------------

### Initialize plx_pci module for NMEA2000 on Network 1

Source: https://gpsd.io/gpsinit.html

Similar to the previous example, but specifies network 1 for the NMEA2000 connection using the plx_pci module.

```bash
gpsinit -n 1 plx_pci
```

--------------------------------

### Systemd Service Configuration for gpsd

Source: https://gpsd.io/troubleshooting.html

Example content for a systemd service file to ensure gpsd runs continuously, as systemd typically starts it only on client request.

```ini
[Unit]
Description=GPS (Global Positioning System) Daemon
Requires=gpsd.socket

```

--------------------------------

### Sample NMEA Sentences

Source: https://gpsd.io/gps-hacking.html

These are example data lines (sentences) transmitted by GPS receivers using the NMEA 0183 protocol. Each sentence contains comma-separated fields, starting with a message type and ending with a checksum for data integrity.

```nmea
$GPGGA,212734,4740.0569,N,12219.6612,W,1,08,74.00,73.9,M,638.000000,M,,*6D
$GPRMC,212734,A,4740.0569,N,12219.6612,W,0.000000,0.000000,020403,18.936255,E*60
$GPGSA,A,3,17,06,23,15,16,18,10,30,,,,,152.00,74.00,133.00*3F
$GPGGA,212735,4740.0569,N,12219.6612,W,1,08,74.00,74.1,M,638.000000,M,,*63
$GPRMC,212735,A,4740.0569,N,12219.6612,W,0.000000,0.000000,020403,18.936255,E*61
```

--------------------------------

### Compile gpsd Client Example

Source: https://gpsd.io/gpsd-client-example-code.html

Instructions for compiling a C example program using the gpsd client library. Requires libgps and gps.h.

```bash
# example  gpsd client
# compile this way:
#    gcc example1.c -o example1 -lgps -lm
#include <gps.h>         .. for gps_*()

```

--------------------------------

### Build and Install gpsd on macOS with Homebrew

Source: https://gpsd.io/building.html

After installing Homebrew, this sequence creates a directory for the source, clones gpsd, and then builds and installs it.

```bash
# mkdir -p /usr/local/src/GPS
# cd /usr/local/src/GPS
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons && scons install
```

--------------------------------

### Display help message

Source: https://gpsd.io/gpsinit.html

Shows a brief help text outlining the available options and usage of the gpsinit command.

```bash
gpsinit -h
```

--------------------------------

### Remove Existing gpsd Installation on Raspberry Pi OS

Source: https://gpsd.io/building.html

Ensure no previous versions of gpsd are installed before proceeding with a source installation. This involves stopping services and purging related packages. Some commands may report errors if gpsd is not already installed, which is normal.

```bash
$ sudo su -
# systemctl stop gpsd.socket
# systemctl disable gpsd.socket
# apt purge gpsd gpsd-clients gpsd-tools
```

--------------------------------

### Display version information

Source: https://gpsd.io/gpsinit.html

Prints the version of the gpsinit utility.

```bash
gpsinit -v
```

--------------------------------

### Install Documentation Build Tools

Source: https://gpsd.io/building.html

Installs asciidoctor, a tool required for building the project's documentation, including the website and man pages.

```bash
apt-get install asciidoctor
```

--------------------------------

### Launch gpsd with Debugging and Device File

Source: https://gpsd.io/troubleshooting.html

Launch gpsd with debugging options and specify a device file. This example shows the output when the device file does not yet exist.

```bash
# gpsd -N -D3 -F @RUNDIR/gpsd.sock /dev/ttyUSB0
gpsd: launching (Version 2.96~dev)
gpsd: listening on port gpsd
gpsd: running with effective group ID 0
gpsd: running with effective user ID 0
gpsd: stashing device /dev/ttyUSB0 at slot 0
^Cgpsd: received terminating signal 2.
gpsd: exiting.
#
```

--------------------------------

### Example MWD Sentence

Source: https://gpsd.io/NMEA.html

Example of a Wind Direction & Speed sentence.

```NMEA
$WIMWD,302.4,T,289.6,M,10.5,N,5.4,M*6F
```

--------------------------------

### Launch gpsd with Device File and Udev Interaction

Source: https://gpsd.io/troubleshooting.html

Launch gpsd with a device file. This example demonstrates the output when udev is active and the device file is subsequently created or accessed.

```bash
# gpsd -N -D3 -F @RUNDIR/gpsd.sock /dev/ttyUSB0
gpsd: launching (Version 2.96~dev)
gpsd: listening on port gpsd
gpsd: running with effective group ID 0
gpsd: running with effective user ID 0
gpsd: stashing device /dev/ttyUSB0 at slot 0
gpsd: control socket connect on fd 6
gpsd: <= control(6): /dev/ttyUSB0 already active
^Cgpsd: received terminating signal 2.
gpsd: exiting.
#
```

--------------------------------

### Example MTW Sentence

Source: https://gpsd.io/NMEA.html

Example of a Mean Temperature of Water sentence.

```NMEA
$INMTW,17.9,C*1B
```

--------------------------------

### Example MSS Sentence

Source: https://gpsd.io/NMEA.html

Example of a Beacon Receiver Status sentence.

```NMEA
$GPMSS,0,0,0.000000,200*5A
```

--------------------------------

### Logging Information (Supported)

Source: https://gpsd.io/ubxtool-examples.html

Example output indicating that the receiver supports logging, showing available filestore capacity and current log status.

```text
    UBX-LOG-INFO:
      version 1 reserved1 x0 x0 filestoreCapacity 487680 reserved2 x9600 x24900
      currentMaxLogSize 134400 currentLogSize 61 entryCount 0
      oldestYear 0 oldestMonth 0 oldestDay 0
      oldestHour 0 oldestMin 0 oldestSec 0 reserved3 x0
      newestYear 0 newestMonth 0 newestDay 0
      newestHour 0 newestMin 0 newestSec 0 reserved4 x0
      status x20 reserved5 x0 x0

```

--------------------------------

### Disable APT Recommended Packages

Source: https://gpsd.io/troubleshooting.html

Prevent APT from installing recommended packages, which can sometimes lead to unwanted installations like gpsd. This is useful when installing packages that recommend gpsd.

```bash
APT::Install-Recommends "false";
```

--------------------------------

### Dump All Configuration Items

Source: https://gpsd.io/ubxtool.html

Retrieve a large range of configuration items, including known and unknown ones, currently in RAM. This example uses wildcards for group and item numbers and pipes the output to 'fgrep' to filter for 'item CFG-'.

```bash
$ ubxtool -g CFG,0,0,1200 | fgrep "item CFG-"
    item CFG-1-1/0x10010001 val 0
    item CFG-1-1/0x10010101 val 0
    item CFG-4-1/0x10040001 val 1
    item CFG-4-2/0x10040002 val 0
    item CFG-4-3/0x10040003 val 0
    item CFG-4-4/0x10040004 val 0
    item CFG-4-9/0x10040009 val 0
    item CFG-TP-TP1_ENA/0x10050007 val 1
    item CFG-TP-SYNC_GNSS_TP1/0x10050008 val 1
[...]
```

--------------------------------

### HWBIAS Example

Source: https://gpsd.io/NMEA.html

An example of an unknown HWBIAS sentence seen from Huawai GPS receivers.

```nmea
$GPHWBIAS,11.2*21
```

--------------------------------

### HDT Example

Source: https://gpsd.io/NMEA.html

An example of an HDT sentence indicating a true heading of 274.07 degrees.

```nmea
$GPHDT,274.07,T*03
```

--------------------------------

### GPSD Client Example in C

Source: https://gpsd.io/index.html

A line-by-line code walk-through of a simple gpsd client written in C. Focuses on common mistakes.

```c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

#define SERVER "127.0.0.1"
#define BUFLEN 512
#define PORT 2947

int main(void)
{
    struct sockaddr_in si_other;
    int s, i, slen=sizeof(si_other);
    char buf[BUFLEN];
    char message[BUFLEN];

    // Create socket
    if ((s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
    {
        die("socket");
    }

    memset((char *) &si_other, 0, sizeof(si_other));
    si_other.sin_family = AF_INET;
    si_other.sin_port = htons(PORT);
    if (inet_aton(SERVER, &si_other.sin_addr) == 0)
    {
        fprintf(stderr, "inet_aton() failed\n");
        exit(1);
    }

    // Send some data
    strcpy(message, "?WATCH={"driver=nmea"}");
    if (sendto(s, message, strlen(message), 0, (struct sockaddr *) &si_other, slen) == -1)
    {
        die("sendto");
    }

    // Receive data
    while (1)
    {
        printf("Waiting for packet...\n");
        fflush(stdout);

        // Try to receive some data, this is blocking call
        if (recvfrom(s, buf, BUFLEN, 0, (struct sockaddr *) &si_other, &slen) == -1)
        {
            die("recvfrom");
        }

        printf("Received packet: %s
", buf);
    }

    close(s);
    return 0;
}

```

--------------------------------

### DPT - Depth of Water Example

Source: https://gpsd.io/NMEA.html

Example of a Depth of Water sentence from an INDPT device.

```plaintext
$INDPT,2.3,0.0*46
```

--------------------------------

### Build and Check gpsd on Fedora

Source: https://gpsd.io/building.html

Builds, checks, and installs gpsd on Fedora after dependency installation.

```bash
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons
# dnf builddep -y buildtmp/packaging/rpm/gpsd.spec
# scons -c
# scons && scons check && scons install
```

--------------------------------

### Start Logging

Source: https://gpsd.io/ubxtool-examples.html

Initiates the logging process on the receiver. This command configures the log filter settings.

```bash
$ ubxtool -e LOG
[...] 
sent:
UBX-CFG-LOGFILTER:
 version 1 flags x5 minInterval 0 timeThreshold 0
 speedThreshold 0 positionThreshold 0

UBX-ACK-ACK:
  ACK to Class x06 (CFG) ID x47 (LOGFILTER)
```

--------------------------------

### Build and Install gpsd from Source (Alternative)

Source: https://gpsd.io/building.html

A simplified sequence for cloning the gpsd repository and building/installing it using scons, after necessary dependencies are met.

```bash
# git clone https://gitlab.com/gpsd/gpsd.git
# cd gpsd
# scons -c && scons && scons check && scons install
```

--------------------------------

### VTG Example

Source: https://gpsd.io/NMEA.html

An example of a VTG sentence showing actual measured values for course and speed.

```NMEA
$GPVTG,220.86,T,,M,2.550,N,4.724,K,A*34
```

--------------------------------

### RMC Example

Source: https://gpsd.io/NMEA.html

An example of a $GNRMC sentence, showing a valid fix with specific navigation parameters.

```text
$GNRMC,001031.00,A,4404.13993,N,12118.86023,W,0.146,,100117,,,A*7B
```

--------------------------------

### Install Optional GUI Dependencies (Bullseye)

Source: https://gpsd.io/building.html

Installs libraries for GTK3, which are necessary for running graphical clients like xgps and xgpsspeed. This is an optional step if GUI tools are not needed.

```bash
# apt-get install python-gi-dev
# apt-get install libgtk-3-dev
```

--------------------------------

### DTM - Datum Reference Example

Source: https://gpsd.io/NMEA.html

Example of a Datum Reference sentence specifying the WGS84 datum.

```plaintext
$GPDTM,W84,C*52
```

--------------------------------

### Install Optional Libusb (Bullseye)

Source: https://gpsd.io/building.html

Installs libusb-1.0-0-dev, which is required for supporting some older Garmin USB devices.

```bash
# apt-get install libusb-1.0-0-dev
```

--------------------------------

### Configure and Compile Daemon

Source: https://gpsd.io/writing-a-driver.html

Standard commands to configure and compile the daemon. Ensure you have the necessary build tools installed.

```bash
./configure
make
make install
```

--------------------------------

### Install Optional Matplotlib (Bullseye)

Source: https://gpsd.io/building.html

Installs the python3-matplotlib package, which is a dependency for gpsplot to generate graphical output.

```bash
# apt install python3-matplotlib
```

--------------------------------

### Install Gentoo Build Tools

Source: https://gpsd.io/building.html

Installs essential build tools like scons and git on Gentoo. Use '--noreplace' to avoid reinstalling existing packages.

```bash
# install the required build tools
emerge --noreplace dev-build/scons dev-vcs/git

# optional, to support the KPPS API, for improved timing
emerge --noreplace net-misc/pps-tools

# optional, for cgps and gpsmon
emerge --noreplace sys-libs/ncurses

# optional, for ubxtool and zerl serial port support
emerge --noreplace dev-python/pyserial

# optional, to support Garmin USB devices
emerge --noreplace virtual/libusb

# optional, to support Bluetooth GPS devices
emerge --noreplace net-wireless/bluez

# Skip the following optionals on a minimal system:

# optional, to build man page and html pages
emerge --noreplace dev-ruby/asciidoctor

# Optionals for desktop (X) systems:

# optional, for xgps and xgpsspeed
emerge --noreplace dev-python/pygobject dev-python/pycairo

# optional, for gpsplot
emerge --noreplace dev-python/matplotlib

# D-Bus support
emerge --noreplace sys-apps/dbus

# To build Qt compatible library.
emerge --noreplace dev-qt/qtcore dev-qt/qtnetwork

# "scons check" requires bc
emerge --noreplace sys-devel/bc
```

--------------------------------

### XDR Example

Source: https://gpsd.io/NMEA.html

An example of an XDR sentence reporting pitch, roll, and magnetometer data from different transducers.

```NMEA
$HCXDR,A,171,D,PITCH,A,-37,D,ROLL,G,367,,MAGX,G,2420,,MAGY,G,-8984,,MAGZ*41
```

--------------------------------

### GPSD Client Example in Python

Source: https://gpsd.io/index.html

A line-by-line code walk-through of a simple gpsd client written in Python. Focuses on common mistakes.

```python
import socket
import json

HOST = '127.0.0.1'
PORT = 2947

# Create a socket object
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# Connect to the gpsd server
try:
    s.connect((HOST, PORT))
except socket.error as e:
    print(f"Error connecting to gpsd: {e}")
    exit(1)

# Send a command to start watching for data
command = json.dumps({"enable": True, "json": True}).encode('utf-8')
s.sendall(command + b'\n')

# Receive and print data
while True:
    try:
        data = s.recv(4096).decode('utf-8')
        if not data:
            break
        # gpsd sends data line by line, so we need to handle potential partial lines
        # For simplicity, we'll assume complete lines here, but a real client might need more robust parsing
        for line in data.strip().split('\n'):
            if line:
                try:
                    message = json.loads(line)
                    print(json.dumps(message, indent=2))
                except json.JSONDecodeError:
                    print(f"Received non-JSON data: {line}")
    except socket.error as e:
        print(f"Error receiving data: {e}")
        break

# Close the connection
s.close()

```

--------------------------------

### Android build with custom prefix and directories

Source: https://gpsd.io/building.html

Build command for Android specifying prefix, library directory, udev directory, user, group, and socket export settings.

```bash
scons -j3 prefix=/usr libdir=$prefix/lib udevdir=/lib/udev \
  gpsd_user=gpsd gpsd_group=uucp socket_export=1 sirf=1
```

--------------------------------

### Install Build Dependencies on Fedora

Source: https://gpsd.io/building.html

Installs necessary development tools and libraries for building gpsd on Fedora 32-37.

```bash
# dnf upgrade --refresh
# dnf install -y gcc-c++ scons asciidoctor bzip2
# dnf install -y xz git dnf-plugins-core
```

--------------------------------

### Check Firmware Version (FLASH)

Source: https://gpsd.io/ubxtool-examples.html

Use 'ubxtool -p MON-VER' to check the firmware version. 'swVersion EXT CORE' indicates the firmware is loaded from FLASH memory, allowing for updates.

```bash
$ ubxtool -p MON-VER -P 27.12
[...] 
UBX-MON-VER:
  swVersion EXT CORE 1.00 (f10c36)
  hwVersion 00190000
  extension ROM BASE 0x118B2060
  extension FWVER=HPG 1.13
  extension PROTVER=27.12
  extension MOD=ZED-F9P
  extension GPS;GLO;GAL;BDS
  extension SBAS;QZSS
```

--------------------------------

### Configuring Cross-Build Options

Source: https://gpsd.io/building.html

This snippet demonstrates how to set up cross-compilation by modifying the .scons-options-cache file. It specifies target architecture, sysroot, and installation prefix.

```bash
$ cat .scons-option-cache
libgpsmm = False
libQgpsmm = False
python = False
prefix = '/work/buildroot/output/staging/usr/'
sysroot = '/work/buildroot/output/staging/'
target = 'arm-indigo-linux-gnueabi'
```

--------------------------------

### Install scons and Python on OpenBSD

Source: https://gpsd.io/building.html

Installs scons and Python 3.8 on OpenBSD 13.0, required for building gpsd.

```bash
# pkg install scons-py38
# ln -s /usr/local/bin/python3.8 /usr/local/bin/python3
```

--------------------------------

### GPSD Time Service Setup

Source: https://gpsd.io/index.html

Step-by-step instructions for setting up a Stratum 1 time server using GPSD and either ntpd or chrony. Includes tuning offsets for remote time servers.

```bash
# Example commands for setting up GPSD time service
# Ensure gpsd is installed and configured to output time data
# sudo apt-get install gpsd gpsd-clients ntp

# Configure gpsd to output time
# Edit /etc/default/gpsd and set GPSD_OPTIONS="-n -G"
# Restart gpsd: sudo systemctl restart gpsd

# Configure ntpd to use gpsd as a time source
# Edit /etc/ntp.conf
# Add the following lines:
# server 127.0.0.1 prefer iburst
# fudge 127.0.0.1 time1 0.12345 time2 0.0 timecode 1

# Restart ntpd
# sudo systemctl restart ntp

# Verify time synchronization
# ntpq -p

```

--------------------------------

### Display help message for xgps

Source: https://gpsd.io/xgps.html

Use the -?, -h, or --help option to display a summary of available options and then exit.

```bash
xgps -h
```