Your Terminal Shouldn't Just Be Black and White

Have you ever questioned life while writing a CLI tool or debugging output?

"Why does the information I just printed look like a plain bowl of noodles with no toppings?"

Sorry, I don't mean to offend noodles, I just want to say:

If you want your terminal to be more recognizable and allow you to spot key information at a glance, then you need to get to know a subtle but powerful player:

• ANSI Escape Codes.

What Are They?​

ANSI stands for American National Standards Institute, an organization responsible for setting various standards, including character encoding for computers.

ANSI Escape Codes are sequences of characters that look like random code. They usually begin with \033[ or \x1b[, followed by various control codes.

Here's an example:

print("\033[1;31mHello World\033[0m")

This code will print "Hello World" in bold red text. The \033[0m at the end is a reset code, preventing the following output from being affected by the red color.

Common Formatting Control Codes​

You can use these values to style the text:

These can be combined with colors to create a "personalized outfit" for your CLI.

print("\033[5;31mThis is a slow-blinking red text\033[0m")

Color Control Codes​

The text color codes in ANSI Escape Codes typically range from 30–37 (standard colors) and 90–97 (bright colors).

Here is the corresponding table:

Background color codes correspond to 40–47 (standard colors) and 100–107 (bright colors), and they follow the same pattern as above:

You may notice that codes from 38 to 89 are rarely mentioned — so where did they go?

• 38 and 48: Advanced Usage for Custom Colors

  • 38 = Enable "custom foreground color" mode
  • 48 = Enable "custom background color" mode

  At this point, you need to specify the color with additional parameters, such as 256 colors (8-bit mode):

  print("\033[38;5;198mA pink text\033[0m")
  
  • 38;5;198 refers to color number 198 from the 256-color palette.

  Or, use True Color (24-bit mode):

  print("\033[38;2;255;105;180mHello in pink!\033[0m")
  
  • 38;2;<r>;<g>;<b> allows you to precisely specify RGB values.

• 39 and 49: The Reset Color Friends

  • 39: Reset to the default foreground color
  • 49: Reset to the default background color

So, let’s summarize the color code map:

Here’s a program to play around with:

for i in range(256):
    print(f"\033[48;5;{i}m {i:3} \033[0m", end=" ")
    if i % 16 == 15:
        print()

After running it, it will look something like this:

Combination Syntax Examples​

The syntax format is:

\033[<format>;<text color>m

Example:

def colorstr(text, fmt=1, color=34):
    return f"\033[{fmt};{color}m{text}\033[0m"

print(colorstr("This is a bold blue text"))

A bit trendier:

print("\033[1;34;43mBlue text on yellow background, fashion explained\033[0m")

Notes​

There are a few things to keep in mind when using color so that your output doesn't turn into a disaster:

• Always reset: Without \033[0m, your output will inherit the color, turning a simple red message into a long red novel.
• Jupyter has many limitations: While it can display color, cursor control and screen manipulation are mostly a dream.
• Windows Terminal has been updated: The new version finally does a good job; for the old version, use colorama.
• Don’t mess with log files: Unless you enjoy torturing yourself with regular expressions, it's better to save the text as plain text.

Extended Applications​

You can wrap your own color utility module and even use Enum to write a cleaner call method:

from enum import Enum

class COLOR(Enum):
    RED = 31
    GREEN = 32
    BLUE = 34

class FORMAT(Enum):
    BOLD = 1
    UNDERLINE = 4

def colorstr(obj, color=COLOR.BLUE, fmt=FORMAT.BOLD):
    return f"\033[{fmt.value};{color.value}m{obj}\033[0m"

Application scenarios:

• Error and warning messages: Use red to say “There’s a problem here.”
• Success messages: A green checkmark is just delightful.
• Interactive menu prompts: Let the user know what to enter next.

Don’t Want to Handle It Yourself?​

Many libraries have already packaged this for you, so you can use them directly.

Here are a few Python libraries you can refer to:

1. colorama

   Solves cross-platform display issues, a Windows helper, and is easy to use:

   from colorama import init, Fore, Style
   init()
   print(Fore.RED + "Hello in red!" + Style.RESET_ALL)
   

2. termcolor

   Provides colored(), no fuss:

   from termcolor import colored
   print(colored("Warning", "red", attrs=["bold"]))
   

3. rich

   Supports colors, tables, progress bars, Markdown—it's like React for CLI.

   from rich import print
   print("[bold red]This is a bold red text[/bold red]")
   

Summary​

Mastering ANSI Escape Codes is like adding a color palette to your terminal.

From debugging to CLI tool development, you can create the most eye-catching effects with minimal tools.

More importantly, it allows users to quickly recognize "red is an error," "green is good," and "yellow means wait," without getting lost in a sea of black-and-white messages.

Make the terminal world colorful, starting with \033[.

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