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C++ CMake Syslog Dashboard

View source on GitHub

This guide walks you through building and running the C++ CMake syslog dashboard reference on Avocado OS. The app reads the systemd journal and renders a live TUI with message rates, severity breakdowns, and top logging units.

Prerequisites​

  • macOS 10.12+ or Linux (Ubuntu 22.04+, Fedora 39+)
  • Docker Desktop installed and running
  • The latest version of the Avocado CLI

For hardware targets, you will also need:

  • Your target device and any required accessories (SD card, USB cable, serial console adapter)
  • See the Support Matrix for your target's requirements

Initialize​

Clone the reference or initialize a new project from it:

avocado init --reference cpp-tui-dashboard cpp-tui-dashboard
cd cpp-tui-dashboard

To target specific hardware instead of the default, pass --target:

avocado init --reference cpp-tui-dashboard --target raspberrypi5 cpp-tui-dashboard
cd cpp-tui-dashboard

Install​

Install the SDK toolchain, extension dependencies, and runtime packages:

avocado install -f

This pulls the SDK container image and installs the cross-compilation toolchain along with nativesdk-cmake.

Build​

Build the extensions and assemble the runtime image:

avocado build

The build step runs app-compile.sh inside the SDK container, which generates a CMake toolchain file from the SDK environment, fetches FTXUI via FetchContent, and cross-compiles the dashboard binary. Then app-install.sh copies the binary into the extension sysroot at /usr/bin/syslog-dashboard.

Deploy​

QEMU​

For QEMU targets, provision and boot the VM:

avocado provision -r dev
avocado sdk run -iE vm dev

SD card targets (Raspberry Pi, Seeed reTerminal, NXP, STMicroelectronics)​

Insert your SD card and provision:

avocado provision -r dev --profile sd

Insert the SD card into the device and apply power.

USB flash targets (OnLogic)​

avocado provision -r dev --profile usb

NVIDIA Jetson​

avocado provision -r dev --profile tegraflash

Follow the USB disconnect/reconnect prompts during the flash process.

Verify​

Log in as root with an empty password. The app service starts automatically on boot. When running as a service (no TTY), it logs periodic summaries to the journal.

Check the service is running:

systemctl status app

Watch the headless output:

journalctl -u app -f

You should see output like:

syslog-dashboard: 142 total | 8 msg/s | ERR:2 WARN:15 INFO:125

Interactive TUI​

For the full terminal dashboard, SSH into the device and run it directly:

syslog-dashboard

You will see a live dashboard with:

  • A message rate sparkline (60-second window)
  • Severity counters (EMERG through DEBUG, color-coded)
  • Top logging units ranked by message count
  • A scrolling list of recent journal entries

Press q to quit.

Customize​

Change the journal filter​

Edit app/src/main.cpp and modify the journalctl command in the journal_reader function to filter by unit, priority, or time range:

// Only show errors and above
FILE* pipe = popen("journalctl -f -o export --no-pager -p err 2>/dev/null", "r");

// Only show a specific unit
FILE* pipe = popen("journalctl -f -o export --no-pager -u myapp.service 2>/dev/null", "r");

Adjust the UI refresh rate​

The UI refreshes every 500ms by default. Change the interval in the run_tui function:

std::this_thread::sleep_for(std::chrono::milliseconds(250));  // faster refresh

Rebuild after changes​

After any change, rebuild and reprovision:

avocado build
avocado provision -r dev