Shell

ANSI Colors

The color of text and/or the background of text can be modified by using ANSI color codes. Use echo with escape codes enabled to display various different colors.

$ echo -e "\033[32mHello green world\033[0m"

Basic text colors:

  • Black = \033[30m

  • Blue = \033[34m

  • Cyan = \033[36m

  • Green = \033[32m

  • Magenta/Purple = \033[35m

  • Orange = \033[33m

  • Red = \033[31m

  • White = \033[37m

Basic background colors [1]:

  • Black = \033[40m

  • Blue = \033[44m

  • Cyan = \033[46m

  • Green = \033[42m

  • Magenta/Purple = \033[45m

  • Orange = \033[43m

  • Red = \033[41m

  • White = \033[47m

Notice that gray is not a valid ANSI color. [2]

Reset codes [1][4]:

  • Text only = \033[39m

  • Background only = \033[49m

  • Text and background = \033[0m

Understanding ANSI color codes:

  • Example (red background text): \033[41m

    • \033 (octal) or \x1b (hexadecimal) is the escape sequence that denotes that this is an ANSI color code. [5]

    • [ or [0; by default means that no special stylization is applied. Alternatives include [3]:

      • [1; = bold.

      • [2; = low intensity.

      • [3; = italicize.

      • [4; = underline.

      • [9; = high intensity.

    • 4 denotes background color. Alternatives include:

      • 3 = text color.

      • 10 = high intensity background color.

    • The last number 1 denotes the actual color.

    • m denotes the end of the ANSI color code.

Zsh

Differences with Bash

  • Arrays are used differently.

    • Bash:

      CMD=(echo Hello world)
${CMD[*]}

    • Zsh:

      CMD=(echo Hello world)
$CMD

  • If nothing is found with a wildcard * blob, then Zsh will fail and exit the script immediately. This is because Zsh itself tries to expand it instead of sending the wildcard to the application. Use setopt to make the behavior the same as Bash. [6]

    setopt +o nomatch
ls /tmp/foobar*

  • Zsh will always preserve newlines when outputting a variable. However, Bash will only preserve newlines when the variable is quoted. [7]

    $ foobar=$(echo -e "foo\nbar")
$ echo ${foobar}
$ echo "${foobar}"

    foo bar
foo
bar

History

Bibliography

  1. “How to change the color of your Linux terminal.” Opensource.com. September 19, 2019. Accessed July 31, 2023. https://opensource.com/article/19/9/linux-terminal-colors

  2. “The entire table of ANSI color codes.” GitHub iamnewton/bash-colors.md. February 20, 2023. Accessed July 31, 2023. https://gist.github.com/iamnewton/8754917

  3. “The entire table of ANSI color codes working in C!” GitHub RabaDabaDoba/ANSI-color-codes.h. July 10, 2023. Accessed July 31, 2023. https://gist.github.com/RabaDabaDoba/145049536f815903c79944599c6f952a

  4. “How to stop the effect of ANSI text color code or set text color back to default after certain characters?” Stack Overflow. April 21, 2023. Accessed July 31, 2023. https://stackoverflow.com/questions/43539956/how-to-stop-the-effect-of-ansi-text-color-code-or-set-text-color-back-to-default

  5. “How do I print colored text to the terminal in Rust?” Stack Overflow. January 24, 2023. Accessed July 31, 2023. https://stackoverflow.com/questions/69981449/how-do-i-print-colored-text-to-the-terminal-in-rust

  6. “Why zsh tries to expand * and bash does not?” Stack Overflow. May 7, 2022. Accessed February 20, 2024. https://stackoverflow.com/questions/20037364/why-zsh-tries-to-expand-and-bash-does-not

  7. “How to preserve line breaks when storing command output to a variable? [duplicate].” Stack Overflow. August 9, 2023. Accessed February 20, 2024. https://stackoverflow.com/questions/22101778/how-to-preserve-line-breaks-when-storing-command-output-to-a-variable