Terminals, Shells, and Prompts

This post, the first in this series, is long overdue and is a collection of my findings. This is likely only a snapshot of my current set up, but I’m hoping that someone finds this useful. By the end of this post you should know a bit more about terminals, shells, prompts, escape codes, and their interactions. In the following posts I’ll show you my configuration and how you can copy the parts you like.

Why does this matter? #

I regularly work on multiple OS’s in my day-to-day job, and I need to be able to quickly jump between any of them. Context switching can cost time, and lead to mistakes. It’s also annoying when a keyboard combo works on one OS/Shell/etc. and not another. While making the terminal consistent between OS’s doesn’t solve all the costs of context switching, it does make the experience more enjoyable.

My goals #

These are my overall goals with my particular setup.

1. Configs that I can sync between computers of any OS.
2. Allow flexibility to add machine/environment specific options (e.g. work).
3. Allow ability to swap any component when I see the next new shiny thing.

Crash Course on Terminals, etc #

I want this to be as accessible as possible, so I’ll “briefly” explain each component and their interactions with each other. Also, as an engineer, I have to explain all the details or else my brain hurts. The examples given are a VERY small subset of the options out there. I may also over simplify many concepts, feel free to let me know in the comments.

Terminals #

The terminal is the application used to communicate and display information for a system(s). These applications can connect to a Shell on a local or remote machine.

Some examples are:

• WezTerm ( )
• Windows Terminal ( )
• ConEmu ( )
• Terminal ( )
• iTerm2 ( )
• So many more…

Shells #

The shell is the user interface used by a terminal to interpret commands from you the user.

Some examples are:

• PowerShell ( )
• Windows PowerShell ( )
• Bash ( )
• ZSH ( )
• Cmd ( )
• Fish ( )

Prompt #

The prompt is what your shell returns to you and can either be a simple character (e.g., $, >, etc.) or something more complex. Prompts are typically written for a specific shell, but some do support multiple.

Some examples are:

• Starship (many shells - written in Rust)
• Oh My Zsh (zsh only)
• Oh My Posh (many shells - written in Go)

Escape Codes #

Escape codes are ways to give your shell a set of instructions. Some of these are known as “Operating System Commands” (aka OSC codes). Often, you get “shell integration” through the use of these codes. While it’s possible to pass the codes yourself at the terminal, it’s more likely you’ll include them in your prompt.

• ANSI Escape Code
• WezTerm Shell Integration
• iTerm2 Shell Integration
• Windows Terminal Shell Integration

Colors: ANSI and Unicode #

Using ANSI color codes (which are special escape codes) is a way to apply colors to your terminal. These codes tell your terminal to use a certain color for foreground or background. Most terminals offer a way to theme your shell by replacing a standard color (i.e., black, bright red, etc.) with specific color in the terminals expected format (i.e., 256-color, hex, etc.). Another way to apply color is to use Unicode character that your shell can interpret as a color. Some shells or prompts offer easy ways to color your prompt.

• Wikipedia: ANSI Escape Codes
• PowerShell Core offers PSStyle

Hopefully this was informative and has helped you understand how these different components interact. The next post in this series is My Terminal: WezTerm.

Cover Photo by Philipp Katzenberger on Unsplash