USER variable in cron

[Lubos Vrbka <lubos.vrbka@gmail.com>]

hi guys,

i realized that the $USER variable isn't defined in cron jobs running 
under my user. however, e.g., $HOME is defined. is there any explanation 
why $USER isn't defined?

in my case the following script added to my crontab
#!/bin/sh
echo debug
echo home ${HOME}
echo user ${USER}
echo debug finished

results in
debug
home /home/vrbka
user
debug finished

i didn't any reference to these variables in cron. thanks for any hints.

regards,

--
Lubos
_@_"