how to enable ls highlighting in Debian

alias ls='ls --color=auto'

Put it in your .bashrc

Or if you prefer create a file in your profile named .bash_aliases and put there your alias (by default in debian's .bashrc that gets sourced)

Under Debian and derivatives (example: raspbian for Raspberry Pi), if you edit the /root/.bashrc file you'll find some line commented about "ls colorization". Just uncomment them and run "source /root/.bashrc" or relogin:

# You may uncomment the following lines if you want `ls' to be colorized:
export LS_OPTIONS='--color=auto'
eval "`dircolors`"
alias ls='ls $LS_OPTIONS'
alias ll='ls $LS_OPTIONS -l'
alias l='ls $LS_OPTIONS -lA'