Creating Conky text variables with zero padding?

Question

I've got a strange issue with my Conky setup:

What I'm looking to get rid of/fix is the fact that my CPU percentages (using ${cpu cpuX}) won't seem to pad properly. I'd like all values to be aligned vertically so that statuses never wiggle. Here's excerpts from my conky file:

# ...
pad_percents 3
# ...
${cpubar cpu1 6,135}$alignr${...}${cpu cpu1}%

How can I right align and pad CPU percentage values so they stop throwing off my layout? The equivalent printf would be %3.0f so that values will appear like this:

$ "%3.0f" % (1,) 
'  1'
$ "%3.0f" % (13,)
' 13'
$ "%3.0f" % (100,)
'100'

How can I make this happen in Conky for my CPU percentage?

Answer 1

A solution provided by @jasonwryan above:

1. Create a Lua script for Conky to use. I created mine in a folder I made in ~/.config/conky/scripts, but you can create yours wherever you'd like:

   $ mkdir -p ~/.config/conky/scripts/
   $ vim ~/.config/conky/scripts/conky_lua_scripts.lua
   

2. Fill the file with the following Lua function:

   function conky_format( format, number )
       return string.format( format, conky_parse( number ) )
   end
   

3. Import your Lua script file into your Conky configuration file using the lua_load directive

   # ...
   lua_load ~/.config/conky/scripts/conky_lua_scripts.lua
   
   TEXT
   # ...
   

4. Whenever you'd like to format a value, call the format function we defined earlier. Note that though we named it conky_format, we access it as format using the lua_parse variable:

   # ...
   lua_load ~/.config/conky/scripts/conky_lua_scripts.lua
   
   TEXT
   # ...
   ${lua_parse format %3.0f ${cpu cpu1}}%
   

This nice script allows you to call into Lua formatting engine with any value and format string. The output now looks as expected:

If you're familiar with printf, you can use the utility to do other awesome formatting hacks.

Answer 2

Almost same effect can be achieved also without lua script by using conditions:

${if_match ${cpu cpu1} < 10}${offset 10}${cpu cpu1}%

Your code would be something similar to:

${cpubar cpu1 6,135}$alignr${...}${if_match ${cpu cpu1} < 10}${offset 10}${endif}${cpu cpu1}%

Note: Offset value (in above case 10) needs to be tweaked according to used font.

More complete example can also use more conditions:

${cpubar cpu1 6,135}$alignr${...}${if_match ${cpu cpu1} < 10}${offset 20}${else}${if_match ${cpu cpu1} < 100}${offset 10}${endif}${cpu cpu1}%