How to make username in terminal smaller?

You need to alter PS1 variable in your environment. PS1 is responsible of how fancy your command prompt will look alike, and what information it will contain.

Permanent change

Following is the excerpt of default .bashrc file in Ubuntu 10.04 LTS:

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi

This makes command prompt look like this: username@hostname:~/directory$

If you change this and delete @\h part in PS1, you will get rid of hostname part in your command prompt:

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u:\w\$ '
fi

Result: username:~/directory$

Temporary change

Override PS1 in your current bash session:

export PS1="\u:\w\$ "

Resources:

• man bash
• How to: Change / Setup bash custom prompt (PS1)
• Color Bash Prompt

See man bash and look for PS1.

To reduce the prompt to the user name, you can add this to your ~/.bashrc:

PS1='\u $'

Some "advanced" customizations see e.g. : Bash Shell PS1: 10 Examples to Make Your Linux Prompt like Angelina Jolie