This is all about the Linux environment variable PS1.

You can customize the shell prompt by editing your PS1 value in the ~/.bashrc file.
For example, add this line to the ~/.bashrc file:

export PS1="\[\e[0;33m\]\u@\h:\[\e[m\]\[\e[0;34m\]\W\[\e[m\]\$ "

The PS1 variable

To check your current PS1 value

$ echo $PS1
PS1="\u@\h:\W\$ "

Useful characters

character value
\u username
\h hostname
\w full path of PWD
\W base name of PWD
\d date in format “Tue May 26”
\D{format} date with specified foramt
\n new line
\t current time in 24-h format “HH:MM:SS”
\T current time in 12-h format “HH:MM:SS”
\@ current time in 12-h format “am/pm”
\A current time in 24-h format “HH:MM”
\$ if the effective UID=0 it’s a “#”, otherwise a “$”
\[ start of nun-printing characters
\] end of nun-printing characters

Reference and also a more complete list here.

Change color

To change the color of your prompt, you can use color code. For example:

PS1="\e[0;33m\u@\h:\W\$ \e[m"

Here in the middle we have "\u@\h:\W\$ " just the same as original PS1. But it is surrounded by color code. The table below explains what those additional characters do.

character meaning
\e[ start of color information
x;ym color codes
\e[m start of color information

Here we use x=0 and y=33, which change the color of our prompt into brown. To customize, you can find the color code in the tables below.

y value color
30 black
31 red
32 green
33 brown
34 blue
35 purple
36 cyan
x value effect
0 normal
1 bold/light
2 dim
4 underlined
… …

Hope you can understand what the example line in Abstract section does now.

export PS1="\[\e[0;33m\]\u@\h:\[\e[m\]\[\e[0;34m\]\W\[\e[m\]\$ "

It generate a prompt:

username@hostname:directory$
<------brown-----><--blue->

Notes

In case the shell cannot correctly calculated the length of the prompt, surround all the non-printing characters with \[ and \].

bad example

PS1="\e[0;33m\u@\h:\W\$ \e[m"

good example

PS1="\[\e[0;33m\]\u@\h:\W\$ \[\e[m\]"

References