Watch the syslog in real time and highlight cases of ERROR or WARN showing up in them using grep color. The blank pattern in the regex 'or' will ensure you see all lines.
sudo tail -F /var/log/syslog | egrep --line-buffered --color=auto 'ERROR|WARN|$'
@climagic What about `journalctl -f` ? There are good options for filtering the syslog with journalctl.
@josemanuel @kaip I'm not strictly universal nor always POSIX compliant in my posts. I've stated a few times before that I'm mostly focused on bash on GNU/Linux because that's what I'm mostly familiar with. Bash also has the widest audience on Linux. While I do try to make stuff universal, that's impossible due to all the varieties and the SysV vs. BSD vs GNU split of options. If I know something is specifically GNU, then I try to put a #GNU hashtag in the post.
@josemanuel @climagic They will have to use something else.