Identifying the boot disk in AIX and HPUX

# bootinfo -b :Command to identify the present boot disk in IBM AIX.

# bootinfo -d :Command to identify the last boot disk  in IBM AIX.

# setboot -v : Command displays the Hardware path the of the primary and alternate boot disk in HPUX.

# ioscan -funH <Hardware_path> -C disk : Command to get the disk on the path in HPUX..

# lvlnboot -v : Command get the boot disk in HPUX..

Virtual Home Directory

In UNIX, a user can login only when they have an account in the server which has an entry at /etc/passwd and other files.

The default location where the user logs in is their respective home directory /home/<username> execpt the "
root". "Root" user logs into "/".

The home directory is created when the # useradd command is used with "-m" flag.

#useradd -m test : Command creates a user called "test" with the home directory of the same name under "/home".

#useradd test : Command create the user "test" with the default attributes.

So what makes the difference when this is executed:

#su - test
#echo $HOME

On the both the case the output will be "/home/test". But the difference is,

# useradd -m test : Creates a home directory.

#useradd test : Created a virtual directory, that is the directory does not exist in real, but allow the users to login by "#su - test", and the user do not have any control like creating a file / reading a file when they login into the virtual directory.