Viewing Logs

Viewing SolarThing’s log files is a good way to see if anything is going wrong, or to just view debug information to see data.

Let’s assume that we have a program configured in the /opt/solarthing/program/custom_rover directory. To view logs, go ahead and cd:

cd /opt/solarthing/program/custom_rover/logs
ls -l

You will now see all of the logs in the directory. You may see lots of files with a .log.gz extension. Those files are the old log files. There should also be three files that have the current logs: log_summary.log, log_info.log and log_debug.log.

To view info logs:

less -R log_info.log

Note

While you can use nano to view log files, it is not recommended because it will not view colors well and is not good at opening large files. vi and vim are also not good for viewing log files containing color.

Now you can browse around.

You can also look at the logs “live”, by using this command:

tail -f log_debug.log

Note

By default the debug log output is not “flushed” immediately. That means that while viewing it data will be cut off. This is to reduce the amount of time spent writing to disk, which is critical in maintaining a stable system on Raspberry Pis.

If you do not want to switch between less -R and tail -f, you can just use less -R by itself. When you want to start “tailing” a file, just press Shift+F. When you want to go back to browsing the file, just press CTRL+C.

If you want to reload the file while inside of less -R, just type Shift+R (R). less is such a useful tool!

Decompressing logs

As mentioned earlier, old log files have a .log.gz extension. If you need to view these log files, you must first decompress them.

Here is an example of how to decompress a particular log file:

gunzip -k log_debug_2022.03.20-1.log.gz
less -R log_debug_2022.03.20-1.log.gz