pdftex (part of the te_pdf package which you hopefully installed in Section 3.5) uses a file pdftex.cfg (located in
/var/lib/texmf/pdftex/config/pdftex.cfg on my system), which contains amongst other things the names of the so-called “map files”. There is currently only one of these files there,
pdftex.map (located in /var/lib/texmf/dvips/config/pdftex.map on my system). It contains the mapping between the short names (like hlsu8r) and the long
PostScript® names (like LucidaSans-Bold) of the fonts. It must contain the mappings for the Computer Modern fonts (lines like “ cmr9 CMR9 <cmr9.pfb”), in order to be able to use
them in PDF. Normally, this is already done by your distribution and you don't need to change anything.
On other systems, the mapping for the Computer Modern fonts may be located in a different file (perhaps under the name cm.map). Check your TeX/LaTeX documentation.
