O comando fc-cache -v -f serve, de uma forma simplista, para verificar no seu sistema quais os tipos de fontes disponíveis para uso.
Para um usuário o correto seria colocar a pasta com a fonte desejada em:
/home/seu_usuário/.fonts
Agora se você deseja para todos os usuários, o correto seria colocar (como root) a pasta da nova fonte em:
/usr/share/fonts/
Ser for uma fonte do tipo truetype sua pasta deveria ser colocada (como root) aqui:
/usr/share/fonts/truetype/
O arquivo conkyrc que como falei é um arquivo de configuração com as intruções para o conky, já especifica qual será a fonte a ser utilizada pelo conky e caso ela não exista no seu sistema vai dar erro, por isso o próprio pacote conky-colors já traz uma pasta de fontes e que se deve colocar em .fonts na sua pasta de usuário e depois usar o comando:
fc-cache -v -f
para atualizar a lista das possíveis fontes que podem ser utilizadas.
A título de exemplo de um arquivo de configuração conkyrc gerado pelo conky-colors:
######################
# - Conky settings - #
######################
update_interval 1
total_run_times 0
net_avg_samples 1
cpu_avg_samples 1
imlib_cache_size 0
double_buffer yes
no_buffers yes
format_human_readable
#####################
# - Text settings - #
#####################
use_xft yes
xftfont Droid Sans:size=8
override_utf8_locale yes
text_buffer_size 2048
#############################
# - Window specifications - #
#############################
#own_window_class Conky
own_window yes
own_window_type override
#own_window_argb_visual yes
#own_window_argb_value 180
own_window_transparent yes
own_window_hints undecorated,below,sticky,skip_taskbar,skip_pager
alignment top_right
gap_x 25
gap_y 35
minimum_size 190 600
maximum_width 190
default_bar_size 60 8
#########################
# - Graphics settings - #
#########################
draw_shades no
draw_borders no
border_width 1
border_margin 5
draw_graph_borders yes
draw_outline no
stippled_borders 0
default_color 353535
color0 black
color1 black
color2 black
TEXT
${font Droid Sans:style=Bold:size=8}SISTEMA $stippled_hr${font}
##############
# - SYSTEM - #
##############
${color0}${voffset 6}${font OpenLogos:size=19}u${font}${color}${goto 32}${voffset -14}Kernel: ${alignr}${color2}${kernel}${color}
${goto 32}Atividade: ${alignr}${color2}${uptime}${color}
# |--CPU
${offset 1}${color0}${font Poky:size=16}P${font}${offset -19}${voffset 9}${cpubar cpu0 4,18}${color}${voffset -16}${goto 32}CPU1: ${font Droid Sans:style=Bold:size=8}${color1}${cpu cpu1}%${font} ${alignr}${font Droid Sans:style=Bold:size=8}${color1}${execi 30 sensors | grep 'Core 0' | cut -c15-16}°C${color}${font} ${color2}${cpubar cpu1 8,50 CE5C00 E07A1F}${color}
${goto 32}CPU2: ${font Droid Sans:style=Bold:size=8}${color1}${cpu cpu2}%${font} ${alignr}${font Droid Sans:style=Bold:size=8}${color1}${execi 30 sensors | grep 'Core 1' | cut -c15-16}°C${color}${font} ${color2}${cpubar cpu2 8,50 CE5C00 E07A1F}${color}
# |--MEM
${color0}${font Poky:size=16}M${font}${color}${goto 32}${voffset -7}RAM: ${font Droid Sans:style=Bold:size=8}${color1}$memperc%${color}${font}
${offset 1}${voffset 2}${color0}${membar 4,18}${color}${goto 32}${voffset -2}F: ${font Droid Sans:style=Bold:size=8}${color2}${memeasyfree}${color}${font} U: ${font Droid Sans:style=Bold:size=8}${color2}${mem}${color}${font}
# |--SWAP
${voffset 2}${color0}${font Poky:size=14}s${font}${color}${voffset -8}${goto 32}SWAP: ${font Droid Sans:style=Bold:size=8}${color1}${swapperc}%${color}${font}
${voffset 4}${offset 1}${color0}${swapbar 4,18}${color}${voffset -4}${goto 32}F: ${font Droid Sans:style=Bold:size=8}${color2}$swapmax${color}${font} U: ${font Droid Sans:style=Bold:size=8}${color2}$swap${color}${font}
#############
# - CLOCK - #
#############
${voffset 4}${font Droid Sans:style=Bold:size=8}DATA $stippled_hr${font}
${voffset 4}${goto 32}${font clockfaces:size=40}O${font}
${voffset -34}${goto 41}${font zoraclockH:size=30}${color2}${execpi 120 /usr/share/conkycolors/bin/conkyClock hour}${color}${font}
${voffset -39}${goto 35}${font zoraclockM:size=40}${color2}${execpi 60 /usr/share/conkycolors/bin/conkyClock minute}${color}${font}
${goto 100}${voffset -40}${font Droid Sans:style=Bold:size=11}${color2}${time %H}${time :%M}${time :%S}${color}${font}
${goto 100}${voffset -2}${goto 100}${font Droid Sans:style=Bold:size=8}${color2}${time %A}${color}${font}
${goto 100}${time %d %b %Y}${voffset 8}
################
# - CALENDAR - #
################
${voffset -2}${color0}${font Poky:size=16}D${font}${voffset -8}${font Droid Sans:style=Bold:size=7}${offset -17}${voffset 4}${time %d}${font}${color}${font Droid Sans Mono:size=7}${execpi 10800 /usr/share/conkycolors/bin/conkyCalendar}${font}${voffset -14}
##########
# - HD - #
##########
${voffset 4}${font Droid Sans:style=Bold:size=8}HD $stippled_hr${font}
# |--HDTEMP1
${voffset 4}${color0}${font Weather:size=15}y${font}${color}${voffset -3}${goto 32}Temperatura: ${font Droid Sans:style=Bold:size=8}${color1}${execi 120 hddtemp /dev/sda -n --unit=C}°C${color}${font}${alignr}${color2}/dev/sda${color}
${execpi 30 /usr/share/conkycolors/bin/conkyHD1}
###############
# - NETWORK - #
###############
${voffset 4}${font Droid Sans:style=Bold:size=8}REDE $stippled_hr${font}
# |--WLAN0
${if_up wlan0}
${voffset -13}${color0}${font VariShapes Solid:size=14}q${font}${color}${goto 32}${voffset -6}Up: ${font Droid Sans:style=Bold:size=8}${color1}${upspeed wlan0}${color}${font} ${alignr}${color2}${upspeedgraph wlan0 8,60 000000}${color}
${goto 32}Total: ${font Droid Sans:style=Bold:size=8}${color2}${totalup wlan0}${color}${font}
${voffset -2}${color0}${font VariShapes Solid:size=14}Q${font}${color}${goto 32}${voffset -6}Down: ${font Droid Sans:style=Bold:size=8}${color1}${downspeed wlan0}${color}${font} ${alignr}${color2}${downspeedgraph wlan0 8,60 000000}${color}
${goto 32}Total: ${font Droid Sans:style=Bold:size=8}${color2}${totaldown wlan0}${color}${font}
${voffset -2}${color0}${font Poky:size=14}Y${font}${color}${goto 32} ${voffset -2}Sinal: ${font Droid Sans:style=Bold:size=8}${color1}${wireless_link_qual wlan0}%${color}${font} ${alignr}${color2}${wireless_link_bar 8,60 wlan0}${color}
${voffset 4}${color0}${font Poky:size=13}w${font}${color}${goto 32}${voffset -8}Ip local: ${alignr}${color2}${addr wlan0}${color}
${goto 32}Ip externo: ${alignr}${color2}${execi 10800 /usr/share/conkycolors/bin/conkyIp}${color}
# |--ETH0
${else}${if_up eth0}
${voffset -13}${color0}${font VariShapes Solid:size=14}q${font}${color}${goto 32}${voffset -6}Up: ${font Droid Sans:style=Bold:size=8}${color1}${upspeed eth0}${color}${font} ${alignr}${color2}${upspeedgraph eth0 8,60 000000}${color}
${goto 32}Total: ${font Droid Sans:style=Bold:size=8}${color2}${totalup eth0}${color}${font}
${voffset -2}${color0}${font VariShapes Solid:size=14}Q${font}${color}${goto 32}${voffset -6}Down: ${font Droid Sans:style=Bold:size=8}${color1}${downspeed eth0}${color}${font} ${alignr}${color2}${downspeedgraph eth0 8,60 000000}${color}
${goto 32}Total: ${font Droid Sans:style=Bold:size=8}${color2}${totaldown eth0}${color}${font}
${voffset -2}${color0}${font Poky:size=13}w${font}${color}${goto 32}${voffset -4}Ip externo: ${alignr}${color2}${addr eth0}${color}
${goto 32}Ip externo: ${alignr}${color2}${execi 10800 /usr/share/conkycolors/bin/conkyIp}${color}
# |--PPP0
${else}${if_up ppp0}
${voffset -13}${color0}${font VariShapes Solid:size=14}q${font}${color}${goto 32}${voffset -6}Up: ${font Droid Sans:style=Bold:size=8}${color1}${upspeed ppp0}${color}${font} ${alignr}${color2}${upspeedgraph ppp0 8,60 000000}${color}
${goto 32}Total: ${font Droid Sans:style=Bold:size=8}${color2}${totalup ppp0}${color}${font}
${voffset -2}${color0}${font VariShapes Solid:size=14}Q${font}${color}${goto 32}${voffset -6}Down: ${font Droid Sans:style=Bold:size=8}${color1}${downspeed ppp0}${color}${font} ${alignr}${color2}${downspeedgraph ppp0 8,60 000000}${color}
${goto 32}Total: ${font Droid Sans:style=Bold:size=8}${color2}${totaldown ppp0}${color}${font}
${voffset -2}${color0}${font Poky:size=13}w${font}${color}${goto 32}${voffset -4}Ip local: ${alignr}${color2}${addr ppp0}${color}
${else}${voffset 4}${color0}${font PizzaDude Bullets:size=12}4${font}${color}${goto 32}Rede indisponível${voffset 14}${endif}${endif}${endif}