Shell Prompt

What is a "Shell Prompt" on Linux?

The shell prompt is the text that appears on the command line before the area where you can type terminal commands, for example John@Mint:~$ is the default shell prompt format on Linux Mint. It's also called "command prompt," however Windows' default terminal emulator is called "Command Prompt," which makes things a bit confusing.

Shell prompts serve three purposes:

1. When you type a command in the terminal, its output will appear on the terminal. The shell prompt indicates that the output of the command has finished and the user may start typing a new command.
2. The shell prompt helps distinguish commands typed by the user from the output of a program when reading the text on the terminal.
3. Short shell prompts tend to be only a single character long plus a space character, such as a dollar sign ($) or a greater than sign (>). Longer shell prompts can include contextual information for the user. It's common for the shell prompt to indicate the value of the pwd command, i.e. what is the "current directory," as this environment variable affects the behavior of programs. The shell prompt may also include the user's username. Although this may not sound very useful as most people know who they are, it's possible to use some terminal commands to switch from one user to another, including to switch to the root user, which has full power over the system and can do massive damage if you run the wrong command with it.

The shell prompt isn't part of the command that will be interpreted by the shell. It can't be edited or removed from the terminal by pressing the Backspace key. However, it's normally possible to customize the shell prompt to display something else, and there are even programs you can install to display colorful information on your terminal instead of the default information.

Although the shell prompt is normally only part of the last line, it's possible for a custom shell prompt to span one entire line before the area where you type commands, or even to span multiple lines.

Observations

In scripting examples, often the author will write the input after a dollar sign ($) or greater sign (>) that represents the shell prompt and distinguish it from the output of the program. For example:

$ date
Thu Feb 20 11:28:20 PM -03 2025

In the code snippet above, date is meant to be a typed command, and we know this because there is a common shell prompt before it. Meanwhile, the line after it, without the shell prompt, is supposed to be the output of the command.

Quotes

A command prompt, also referred to as a prompt or a shell prompt, is a short, automatically generated text message at the beginning of the command line that serves to (1) inform a user that the system is ready for the next command, data element or other input and (2) help the user plan and execute subsequent operations.

https://www.linfo.org/command_line.html (accessed 2025-02-20)

A shell prompt is the main way to interact with a command line only interface. A typical shell prompt will look something like this:

[username@domain directory]$

It displays the user (username) you are logged in as, the server you are logged into (domain) followed by the current directory (or folder) you are in (directory). All this information is followed by a symbol that simply separates the hostname user and directory from the rest of the prompt. Most systems use a $ symbol, but %, # and > symbols are also used.

https://www.marquette.edu/high-performance-computing/linux-intro.php (accessed 2025-02-20)