bash prompt with current working directory, shorten the if it's long.

.bash_profile

# .bash_profile                                                                                
pwd_prompt () {                                                                                
    maxlen=50                                                                                  
    if (( ${#PWD} > maxlen ))                                                                  
    then                                                                                       
        (( offset = ${#PWD} - maxlen ))                                                        
        echo "...${PWD:offset}"                                                                
    else                                                                                       
        echo "${PWD}"                                                                          
    fi                                                                                         
}                                                                                              
                                                                                               
PS1='---- [\u@\h:$(pwd_prompt)] ----\n\$ '