The man page for notify-send says that the urgency level can be low, normal, or critical:
-u, --urgency=LEVEL
Specifies the urgency level (low, normal, critical).
However, while normal and critical alerts appear (critical ones need to be manually dismissed; normal ones disappear by themselves after a short wait), low ones never appear. This is irritating, as I commonly use alert to let me know when a long-running process has finished.
$ type alert
alert is aliased to `notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e 's/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//')"'
I suppose I could re-write alert, but it seems more sensible to try to work out what's suppressing low-urgency notifications. They used to work. It stopped somewhat recently.
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 22.04.3 LTS
Release: 22.04
Codename: jammy
In a related issue, someone else had it even worse: they could only see critical notifications. I can see normal and critical, but not low. (That question has an answer which does not actually address the issue.)
