If login is successful, you should be presented with a shell prompt (such as ``#'' or ``$'') and can happily roam around your system. However, there are some initial problems with using the system that sometimes creep up.
The most common initial configuration problem is incorrect file or directory permissions. This can cause the error message
Shell-init: permission denied
to be printed after logging in (in fact, any time you see the message ``permission denied'' you can be fairly certain that it is a problem with file permissions).
In many cases, it's a simple matter of using the chmod command to fix the permissions of the appropriate files or directories. For example, some distributions of Linux once used the (incorrect) file mode 0644 for the root directory (/). The fix was to issue the command
# chmod 755 /
as root. However, in order to issue this command, you needed to boot from the installation media and mount your Linux root filesystem by hand---a hairy task for most newcomers.
As you use the system, you may run into places where file and directory permissions are incorrect, or software does not work as configured. Welcome to the world of Linux! While most distributions are quite trouble-free, very few of them are perfect. We don't want to cover all of those problems here. Instead, throughout the book we help you to solve many of these configuration problems by teaching you how to find them and fix them yourself. In Chapter 1 we discussed this philosophy in some detail. In Chapter 4, we give hints for fixing many of these common configuration problems.