TITLE: Shell script to extract colours from macOS Terminal.app 
themes
DATE: 2022-12-29
AUTHOR: John L. Godlee
====================================================================


On macOS, configuration profiles for Terminal.app are stored as 
plist files with the extension .terminal. These files contain XML 
or binary data. The profiles contain, among other settings, the 
colour scheme for the terminal.

I wrote a shell script to extract the colour scheme information as 
RGB255 values for each colour scheme value. The function uses a 
combination of xmlstarlet, awk, and some programs which come with 
macOS, like tr, base64, and plutil.

  [xmlstarlet]: https://xmlstar.sourceforge.net/
  [awk]: https://www.gnu.org/software/gawk/manual/gawk.html

First, I define a function to extract colour values:

    function dict_search() {
        # If colour code found in file
        if grep -q "${1}" "${2}"; then
            xml sel --net -t -v 
"//key[.=\"$1\"]/following-sibling::data[1]" "${2}" |
                tr -d '[:space:]' |
                base64 --decode |
                plutil -convert xml1 - -o - |
                xml sel --net -t -v 
"//dict/array/dict/key[.='NSRGB']/following-sibling::data[1]" |
                tr -d '[:space:]' |
                base64 --decode |
                awk -v var="${1}" 'BEGIN{ ORS=" "; print var } 
                        { for(i=1;i<=3;i++) { printf "%.0f ", 
$i*255 }; printf "\n" }' 
        fi
    }

Going line by line:

-   if grep ... will only run the rest of the function if the 
chosen colour ID is found in the .terminal file.
-   xml sel ... searches for the key (i.e. the chosen colour ID), 
then pulls the contents of the data node which comes directly after 
it.
-   tr -d ... removes all spaces, including new lines, effectively 
concatenating the contents of the node.
-   base64 ... converts the base64 encoded data into text
-   plutil -convert ... converts that into XML
-   xml sel ... extracts the RGB values in the XML
-   tr -d ... as above, removes all spaces and new lines
-   base64 ... as above, converts base64 encoded data into text
-   awk ... prints the name of the colour ID, and the three RGB 
components multiplied by 255 and rounded to convert from a 0-1 
decimal to a 0-255 integer.

Then I create an array containing all the colour IDs of interest:

    colArray=("ANSIBlackColor" "ANSIBlueColor" "ANSICyanColor" 
"ANSIGreenColor" "ANSIMagentaColor" "ANSIRedColor" "ANSIWhiteColor" 
"ANSIYellowColor" "ANSIBrightBlackColor" "ANSIBrightBlueColor" 
"ANSIBrightCyanColor" "ANSIBrightGreenColor" 
"ANSIBrightMagentaColor" "ANSIBrightRedColor" 
"ANSIBrightWhiteColor" "ANSIBrightYellowColor" "BackgroundColor" 
"CursorColor" "SelectionColor" "TextBoldColor" "TextColor")

Finally, to construct the output of the script, firstly printing 
the filename, then running the function for each colour ID, and 
only printing the result to stdout if the function output is not 
empty:

    # Print filepath of theme
    printf "%s\n" "${1}"

    # For each in array, run function
    for i in ${colArray[@]}; do
        # Run function
        out=$(dict_search "${i}" "${1}")

        # If output not empty, print 
        if [ -n "${out}" ]; then
            printf "%s\n" "${out}"
        fi
    done

This produces, for example for my tweaked version of the Smyck 
colour scheme, which I use every day:

  [Smyck]: https://color.smyck.org/

    smyck.terminal
    ANSIBlackColor 0 0 0
    ANSIBlueColor 64 125 153
    ANSICyanColor 32 115 131
    ANSIGreenColor 125 169 0
    ANSIMagentaColor 186 138 204
    ANSIRedColor 184 65 49
    ANSIWhiteColor 161 161 161
    ANSIYellowColor 196 165 7
    ANSIBrightBlackColor 75 75 75
    ANSIBrightBlueColor 141 207 240
    ANSIBrightCyanColor 106 217 207
    ANSIBrightGreenColor 196 241 55
    ANSIBrightMagentaColor 247 154 255
    ANSIBrightRedColor 214 131 124
    ANSIBrightWhiteColor 247 247 247
    ANSIBrightYellowColor 254 225 77
    BackgroundColor 18 21 28
    CursorColor 32 115 130
    SelectionColor 32 115 131
    TextBoldColor 247 247 247
    TextColor 247 247 247

  ![Smyck colour 
scheme.](https://johngodlee.xyz/img_full/terminal_colours/smyck.png)

  ![Smyck colour scheme in the 
terminal.](https://johngodlee.xyz/img_full/terminal_colours/smyck_te
rm.png)