Print environment variables containing color from python

Question

I have a file containing a color table that sets environment variables that I use for zsh prompts. Currently have a python script that takes all the colors found between #color-begin and #color-end. However, I cannot pass python string variables into a python shell invocation and I'm unsure what the problem is.

Something like

pythonStr = "fg_blue"
pythonStr = "$"+fg_blue
os.system("echo + pythonStr")

So far I have found a few examples that pass variables into .sh files, but how does one print out a environment color variable without a .sh file? If this is not possible, why is this the case? Here is the current python code I have and the color codes I would like to print out.

Any help would be greatly appreciated.

printcolor.py

import os
import subprocess

def prcl():

with open("appearance") as f:
    content = f.readlines()

    foo = False

    for line in content:
        line = line.strip(' \n\t')

        # Toggle boolean                                                                                                          
        if "color-" in line:
            foo = not foo

        if foo == True:
            if line is not "" and "#" not in line:
                # Use '=' as a delimiter  
                head, sep, tail = line.partition("=")
                head='"$'+head+'"'

                # prints out blank lines
                os.system("echo "+head)

                #prints literal string
                #print(head)                                                                                                      

environment variables for color

#color-begin

fg_black=%{$'\e[0;30m'%}
fg_red=%{$'\e[0;31m'%}
fg_green=%{$'\e[0;32m'%}
fg_brown=%{$'\e[0;33m'%}
fg_blue=%{$'\e[0;34m'%}
fg_purple=%{$'\e[0;35m'%}
fg_cyan=%{$'\e[0;36m'%}
fg_lgray=%{$'\e[0;37m'%}
fg_dgray=%{$'\e[1;30m'%}
fg_lred=%{$'\e[1;31m'%}
fg_lgreen=%{$'\e[1;32m'%}
fg_yellow=%{$'\e[1;33m'%}
fg_lblue=%{$'\e[1;34m'%}
fg_pink=%{$'\e[1;35m'%}
fg_lcyan=%{$'\e[1;36m'%}
fg_white=%{$'\e[1;37m'%}
fg_blue=%{$'\e[0;34m'%}
fg_purple=%{$'\e[0;35m'%}
fg_cyan=%{$'\e[0;36m'%}
fg_lgray=%{$'\e[0;37m'%}
fg_dgray=%{$'\e[1;30m'%}
fg_lred=%{$'\e[1;31m'%}
fg_lgreen=%{$'\e[1;32m'%}
fg_yellow=%{$'\e[1;33m'%}
fg_lblue=%{$'\e[1;34m'%}
fg_pink=%{$'\e[1;35m'%}
fg_lcyan=%{$'\e[1;36m'%}
fg_white=%{$'\e[1;37m'%}

#Text Background Colors                                                                                                                                                                                                                                                           
bg_red=%{$'\e[0;41m'%}
bg_green=%{$'\e[0;42m'%}
bg_brown=%{$'\e[0;43m'%}
bg_blue=%{$'\e[0;44m'%}
bg_purple=%{$'\e[0;45m'%}
bg_cyan=%{$'\e[0;46m'%}
bg_gray=%{$'\e[0;47m'%}

#Attributes                                                                                                                                                                                                                                                                       
at_normal=%{$'\e[0m'%}
at_bold=%{$'\e[1m'%}
at_italics=%{$'\e[3m'%}
at_underl=%{$'\e[4m'%}
at_blink=%{$'\e[5m'%}
at_outline=%{$'\e[6m'%}
at_reverse=%{$'\e[7m'%}
at_nondisp=%{$'\e[8m'%}
at_strike=%{$'\e[9m'%}
at_boldoff=%{$'\e[22m'%}
at_italicsoff=%{$'\e[23m'%}
at_underloff=%{$'\e[24m'%}
at_blinkoff=%{$'\e[25m'%}
at_reverseoff=%{$'\e[27m'%}
at_strikeoff=%{$'\e[29m'%}

#color-end

Answer 1

There are several minor issues with your Python program, but the main reason why your variables are not expanded is because they are not present in the environment when the Python program is run.

Your appearance file should look like:

export fg_black=$'\e[0;30m'
export fg_red=$'\e[0;31m'
export fg_green=$'\e[0;32m'

The %{..%} is just unnecessary, but export is crucial. Without export, after you source appearance in your shell, those variables are not passed onto a python process when called later from that shell with python printcolor.py.

Another option in zsh would be to use setopt allexport and export all environment variables to a subprocess (subshell), but that can have many undesired effects, so you're safer with individual exports.

After you modify your appearance file, you'll have to tweak color name parsing in Python, perhaps like this (the inner if only):

if line and not line.startswith("#"):
    color = line.split("=")[0].split()[1]
    subprocess.call('echo "${%s}"text' % color, shell=True)