Conventions for different kinds of text is as follows:
If you're going to show the use of a command, format the command so it looks like a user's command line. The prompt must contain the shell type (bash, tcsh, zsh, etc) followed by a $ for commands to be run as a normal (non-root) user or a # for a root user.
A command would then look like this:
bash$ command "run as a normal user" bash# command "run as a root user" tcsh# setenv DISPLAY :0.0