How do I write to the log from shell script?

[Neurophile]

Title says it all. I want to trap certain conditions in a shell script and make sure they show up in the log. Also, how do I set the "severity" of the log message so it gets stored/not stored correctly?

 

[RMerlin]

admin@Stargate88:/tmp/home/root# logger --help
BusyBox v1.20.2 (2016-06-03 14:34:02 EDT) multi-call binary.

Usage: logger [OPTIONS] [MESSAGE]

Write MESSAGE (or stdin) to syslog

    -s    Log to stderr as well as the system log
    -t TAG    Log using the specified tag (defaults to user name)
    -p PRIO    Priority (numeric or facility.level pair)