#!/bin/bash
#
# filename is genpass.sh
#
#   example usage for an eight character password
#       . genpass.sh 8 
#
genpasswd() {
        local l=$1
        [ "$l" == "" ] && l=16
        tr -dc A-Za-z0-9_ < /dev/urandom | head -c ${l} | xargs
}
# you could use a number instead of $1 to set the length 
genpasswd $1