milda@henjoh:~/conf/conf-openttd/openttd-1.6.1-linux-generic-amd64$ ./openttd -D -c ttd1.cfg
dbg: [net] Starting dedicated version 1.6.1
dbg: [net] [core] starting network...
dbg: [net] [udp] initializing listeners
dbg: [net] [core] network online, multiplayer available
dbg: [net] Detected broadcast addresses:
dbg: [net] 0) 192.168.1.255
Error: Failed to find a graphics set. Please acquire a graphics set for OpenTTD. See section 4.1 of readme.txt.
milda@henjoh:~/conf/conf-openttd/openttd-1.6.1-linux-generic-amd64$ cd baseset/
milda@henjoh:~/conf/conf-openttd/openttd-1.6.1-linux-generic-amd64/baseset$ ls
no_music.obm  no_sound.obs  opengfx  openttd.32.bmp  openttd.grf  opntitle.dat  orig_dos_de.obg  orig_dos.obg  orig_dos.obs  orig_win.obg  orig_win.obm  orig_win.obs
milda@henjoh:~/conf/conf-openttd/openttd-1.6.1-linux-generic-amd64/baseset$ cd opengfx/
milda@henjoh:~/conf/conf-openttd/openttd-1.6.1-linux-generic-amd64/baseset/opengfx$ ls
bananas_description.txt  bananas.ini  docs  extra  lang  Makefile  Makefile.config  ogfx1_base.pnml  ogfxc_arctic.pnml  ogfxe_extra.pnml  ogfxh_tropical.pnml  ogfxi_logos.pnml  ogfxt_toyland.pnml  scripts  sprites
milda@henjoh:~/conf/conf-openttd/openttd-1.6.1-linux-generic-amd64/baseset/opengfx$