Where does the "n packages can be upgraded" message come from

[stan]

Lately I have been having issues with machines telling me that thier ar
available upgrades when I log in, that do not appear, after an apt-get
upgrade request. I thought I would look to see if soemthing wasn't updating
this properly, so I went and looked in /etc/profile, thinking that was the
logical place for that to be checked, but thier does not seem to be a check
for that there. 

Where can I find this?

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