Sure. There might be multiple ways of achieving this, but one sure way is to use Cron to schedule the apt-get run when you want it to. If you'd like to install every possible update every day at 00.04 (four minutes after midnight), open console, become root and add crontab entry as follows (all the italic
texts are comments, so only the "normal" written text is actual code or commands):
# go to the last line, then press A (shift-a) to get into Append mode;
# then press enter and to the new line write the following:
04 0 * * * apt-get update && apt-get -q=2 dist-upgrade
# now save the crontab by pressing ESC (press twice if unsure) and
# then type :wq and press ENTER
Now you should have a crontab that updates apt-get package lists four minutes after midnight every day. Note that the above example contains the switch "-q=2" which means "quiet quiet", so apt WILL update everything available, and possibly remove packages if needed, WITHOUT ASKING YOU. I strongly recommend you to add "-d" to the line above, thus causing it to only download the needed packages, and do the actual installation either by hand when you can; this way you could prevent damage from happening if apt decided to install or remove some packages against your will.
If you wish to specify weekdays or days of month, please read
for more information (about the time-defining piece of line that in the above example is "04 0 * * *").