Add terminal support

During the setup of your prompt, you might have encuntered bad rendering of the prompt, like wrong characters display or wrong colors display as shown below:

• The v1, "classic" version

  
  

• The v2, "powerline" version

  
  

This might come from either :

• Bad colors support of your terminal, see Configure your prompt - Colors support
• Bad unicode support of your terminal, see Configure your prompt - Unicode support

In this tutorial, we will see how to check colors and unicode support of your temrinal, update required variables accordingly and propose a merge request to add you terminal to the list of supported terminal.

Check colors support

First things to do is to check what kind of colors support your terminal:

• True colors, i.e. 24 bits colors
• 256 colors
• 8/16 colors

First, let us check the true colors. True colors is colors that can be expressed in the 24 bits colors space, i.e. for instance in hexadecimal value like #ff0000 for red.

To check if your terminal support true colors, you can first see the following page :

• https://gist.github.com/XVilka/8346728

If your terminal is not in the list, this may not means that your terminal does not support true colors. Previous link provide a script to test if your terminal support true which is recalled below:

awk 'BEGIN{
    s="/\\/\\/\\/\\/\\"; s=s s s s s s s s;
    for (colnum = 0; colnum<77; colnum++) {
        r = 255-(colnum*255/76);
        g = (colnum*510/76);
        b = (colnum*255/76);
        if (g>255) g = 510-g;
        printf "\033[48;2;%d;%d;%dm", r,g,b;
        printf "\033[38;2;%d;%d;%dm", 255-r,255-g,255-b;
        printf "%s\033[0m", substr(s,colnum+1,1);
    }
    printf "\n";
}'

If you see something like :

This means that your terminal does not support true colors but is making an approximation of their values.

If you see something like :

This means that your terminal does not support true colors at all.

If your terminal does not support true colors, then you have nothing to do as the prompt will automatically determine the number of supported colors using the command tput colors.

If you terminal does support true colors, you might want to add it to the list of the terminal that support true colors. To do so, you will first need to know the "name" of your terminal.

This can be done with the script which_term.sh which rely on xdotool. You may need to install it. Way to install it depends on your distro.

Once installed, simply run the script which_term.sh at the root of the repo.

# Ask which term we are using
./which_term.sh

The output of the script should be a simple line with the name of your temrinal, like :

• st
• xterm
• urxvt
• terminator
• iTerm.app
• VSCode.app
• etc

This value is the one you should add in the file lib/default_vars.sh in the array TRUE_COLOR_TERM. For instance, if your terminal support true colors and its name is my_term_program, you should update value of TRUE_COLOR_TERM as shown below:

# VARIABLES
# =============================================================================
# Setup array to store supported terminal
local UNICODE_SUPPORTED_TERM=("st" "terminator" "xterm" "iTerm.app")
local TRUE_COLOR_TERM=("st" "terminator" "iTerm.app" "my_term_program")

Check unicode support

Second things to do is to check if your terminal support unicode characters.

To do so, you can see the following page which provide code to test if your terminal support unicode characters:

• https://rosettacode.org/wiki/Terminal_control/Unicode_output

As example, we will take the shell code provided in this page:

unicode_tty() {
  # LC_ALL supersedes LC_CTYPE, which supersedes LANG.
  # Set $1 to environment value.
  case y in
  ${LC_ALL:+y})		set -- "$LC_ALL";;
  ${LC_CTYPE:+y})	set -- "$LC_CTYPE";;
  ${LANG:+y})		set -- "$LANG";;
  y)			return 1;;  # Assume "C" locale not UTF-8.
  esac
  # We use 'case' to perform pattern matching against a string.
  case "$1" in
  *UTF-8*)		return 0;;
  *)			return 1;;
  esac
}

if unicode_tty; then
  # printf might not know \u or \x, so use octal.
  # U+25B3 => UTF-8 342 226 263
  printf "\342\226\263\n"
else
  echo "HW65001 This program requires a Unicode compatible terminal" >&2
  exit 252    # Incompatible hardware
fi

Put this lines in a script, let say test_unicode.sh, then execute it :

# To test bash
bash test_unicode.sh
# To test zsh
zsh test_unicode.sh

If you see this character △, i.e. an empty triangle, this means your actual terminal configuration support unicode.

If you do not see this character, do not loose hope, your terminal might still support unicode. First, check your locale using the command locale:

locale
LANG=en_US.UTF-8
LANGUAGE=
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=

If your locale does not end with UTF-8, then it most likely this come from here. Check your distro documentation to change your locale to an UTF-8 local.

If your local does end with UTF-8, then issue might come from the font your terminal use.

I recommend using one of the NerdFont. Personnaly I use FiraCode which is the one used for all screenshots done. And set your terminal emulator to use one of these fonts.

I also recommend using one these fonts because some default segment character are not official unicode character and so might not be display by most "standard" fonts

Configuration of your fonts used by your terminal emulator depends on it, so please refers to the documentation of your terminal emulator to know how to change the fonts.

If you never manage to see the character △, i.e. an empty triangle, unfortunately this means your terminal emulator is not able to print unicode characters. Or it is able to do so but this might require advanced configuration which can not be adressed here. Please refers to your terminal documentation.

If you finally get to the point where you see the character △, congratulations , this means your terminal is able to support unicode.

So, as for true colors support, you might want to add it to the list of the terminal that support unicode. To do so, you will first need to know the "name" of your terminal.

This can be done with the script which_term.sh which rely on xdotool. You may need to install it. Way to install it depends on your distro.

Once installed, simply run the script which_term.sh at the root of the repo.

# Ask which term we are using
./which_term.sh

The output of the script should be a simple line with the name of your temrinal, like :

• st
• xterm
• urxvt
• terminator
• iTerm.app
• VSCode.app
• etc

This value is the one you should add in the file lib/default_vars.sh in the array TRUE_COLOR_TERM. For instance, if your terminal support true colors and is name is my_term_program, you should update value of UNICODE_SUPPORTED_TERM as shown below:

# VARIABLES
# =============================================================================
# Setup array to store supported terminal
local UNICODE_SUPPORTED_TERM=("st" "terminator" "xterm" "iTerm.app" "my_term_program")
local TRUE_COLOR_TERM=("st" "terminator" "iTerm.app")

# VARIABLES
# =============================================================================
# Setup array to store supported terminal
local UNICODE_SUPPORTED_TERM=("st" "terminator" "xterm" "iTerm.app" "my_term_program")
local TRUE_COLOR_TERM=("st" "terminator" "iTerm.app" "my_term_program")

Ready to publish

Once eveything is done, you might want to propose a merge request to update the list of support terminal.

First take screenshots of your terminal showing it supports unicode and/or true colors. Then prepare a merge request as described in :

• Developers Guidelines-6. Prepare your merge request.

And finally, you can propose your merge request as explain in :

• Developers Guidelines-7. Propose your merge request.