Physics 410: Physics and Astronomy Computer Lab PC/Linux Machines

Please make careful note of the following:

1. You must get an account on the Physics & Astronomy server, physics.ubc.ca before you can get an account on the lnx machines. Undergraduates can get an account on physics by "self-registering" in the Computer Lab. Graduate students, and graduate students ONLY can see Mary Ann Potts, for an account. This account will also provide you with access to lts1 via the X-terminal PCs.
2. Your password on the lnx machines will be the same as your password on physics.ubc.ca.
3. Please do NOT change your password on the lnx machines, unless you think it absolutely essential. If you do change it, it will have to be changed on each of lnx1, lnx2 and lnx3 separately.

Note that your home directory on these machines ("the lnx machines") will be distinct from your home directory on physics.ubc.ca, but that you will have a common home directory on physics.ubc.ca and lts1.physics.ubc.ca. Those of you who had physics accounts prior to approximately August 2003 may find that adjustments need to be made to your shell-start up files to take into account this commonality. Again, contact me if you have any questions in this regard.

At the current time, it is not possible to access your lnx files directly from physics (lts1) or vice versa.

Notes on Linux Desktop Environments: Over the past few years, great progress has been made in equipping Linux with powerful graphical user interfaces (GUIs, window managers) to the core operating system and major applications. When you login to the console of one of the lnx machines, you can select from five such interfaces. I recommend that you use one of the following window managers

• KDE
• Gnome

Initial login procedure: When first logging-in at a console of one of the lnx machines, do the following:

1. Type your username in the login-prompt type-in.
2. Click on the Session icon on the lower task bar, and select either KDE or GNOME.
3. Return the mouse to the login-prompt type-in area, hit Enter, type your password at the prompt, then hit Enter again.

IMPORTANT!!: Note on X-terminal Desktop Environments: At the current time you can only use Gnome, NOT KDE, on the X-terminal PCs. In an ideal world, this would get fixed shortly, but unfortunately the problem has persisted for over a year. (If you do choose KDE from the login window on one of the X-terms, the system will (probably) initiate your login, present you with a KDE start-up wizard, etc., but you will also encounter error-message pop-ups, and eventually will be returned to the login screen.)

Note on lnx home directories: The lnx machines have access to each others' disks via NFS (Network File System). The process of attaching a remote file system to a directory name within the local Unix system (i.e. to a directory name somewhere within the file hierarchy rooted in /) is known as mounting the file system. In a shell, you can generate a listing of all of the file systems currently mounted with the Unix df command. For example, you can see the output of df as executed on lnx1 HERE.

Again, each of you has a single home directory on the lnx machines, and that directory is physically located on one of the machines lnx1, lnx2 or lnx3. (I leave it as an exercise for you to determine on which specific machine yours is located.) Let's consider the case of the ``test'' user jdoe, whose home directory is physically located on lnx1, within the file system /home:

[jdoe@lnx1 ~]$ cd
[jdoe@lnx1 ~]$ pwd
/home/jdoe

[jdoe@lnx1 ~]$ ssh lnx2
Warning: Permanently added 'lnx2,142.103.238.212' (RSA) to the list of known hosts.
jdoe@lnx2's password: 
No mail.
[jdoe@lnx2 ~]$ cd
[jdoe@lnx2 ~]$ pwd
/d/lnx1/home/jdoe

[jdoe@lnx2 ~]$ df | grep lnx1
lnx1:/home            19449328   7048332  11413004  38% /d/lnx1/home

Moreover, things have been set up so that you can use the "long" form of your home directory on all of the machines, so that, for example, jdoe can execute the following:

[jdoe@lnx1 ~]$ cd /d/lnx1/home/jdoe
[jdoe@lnx1 ~]$ pwd
/home/jdoe

Note that the specific name of the local mount point, e.g. /d/lnx1/home, is a matter of convention ('d' for disk, then the hostname, then the remote file system name); other system administrators will use different conventions for NFS mounts.

Finally, as mentioned above, you can access your lnx home directories directly from physics since the /home filesystems on the lnx machines are NFS-mounted on physics as

/d/lnx1/home
/d/lnx2/home
/d/lnx3/home

physics% cd /d/lnx1/home/userid
physics% cd /d/lnx2/home/userid
physics% cd /d/lnx3/home/userid