the regular commands for updating your Synology IPKG installation

# is /volume1/@optware symlinked to /opt ?
$ ~/bin/sl /opt
$ ln -s /volume1/@optware /opt
$ export PATH=/opt/bin:$PATH

If /volume1/@optware is not there at all, go to http://forum.synology.com/wiki/index.php/Overview_on_modifying_the_Synology_Server,_bootstrap,_ipkg_etc

johayek@hayekw $ ssh -A root@DiskStation
DiskStationM> ipkg update
DiskStationM> ipkg upgrade
DiskStationM> ipkg install foobar
DiskStationM> ipkg list
DiskStationM> ipkg list_installed

The packages I am interested in:

DiskStation> ipkg list_installed 
bash - …
coreutils - …
diffutils - …
file - …
findutils - …
less - …
man - …
mlocate - …
ncurses - …
ncursesw - …
rcs - …
rsync - …
vim - …
wget - …
py27-mercurial - …