Computing Info for Ling 645/CMSC 723, Fall 1997
Computing Info for Ling 645/CMSC 723, Fall 1997
Introduction to Computational Linguistics
The aITs Unix cluster
The aITs Unix cluster systems (details below) share a common file
system, common news and mail systems, and common users. This means
users can login to whichever of the systems they want and their same
login id and password will work and their files will be available.
This also means users can do their own "load balancing" by logging in
to whichever system seems to be best for them at the time.
System Details
The cluster machines are as follows:
Alpha Systems
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marlowe.umd.edu
marple.umd.edu
tracy.umd.edu
wolfe.umd.edu
holmes.umd.edu
All mail sent to the cluster should be addressed to
login-id@umd5.umd.edu (which is the address that is placed on all
outgoing cluster mail). Mail sent in this manner can be read from any
cluster system. The machine known as umd5.umd.edu is also part of the
cluster but acts as a server for the cluster. DO NOT USE UMD5 for
anything other than your EMAIL address. Never login to umd5.
Games, IRC, and MUDs are not allowed on the aITs Unix cluster.
The home directories contain default .login, .cshrc, and .logout
files. In addition, the access mode on the home directories has been
set to 700. This means that a student will not be able to copy files
from an unsuspecting student, unless the owner changes the mode of his
home directory to something that allows such access. Of course
students can still MAIL things to each other.
User files are NFS mounted on various servers. Symbolic links are
used to create the file names found in the system password file. This
means the names returned by the pwd command may not match the names
found in the system password file. Users should always refer to home
directories by the ~loginid or $HOME methods.
Ethics
All students should read the University of Maryland
Guidelines for the Acceptable Use of Computing Resources
and the
AITS Computer Use Guidelines.
System Access
The only access to the aITs Unix systems is via the campus
network.
WAM (Workstations At Maryland) workstations, such as those
located in CSS room 3330, are directly connected to the campus
network. Directions for using WAM workstations can be found in each
workstation laboratory and in the aITs Information Technology Library
(CSS West Wing room 1400).
Help
Academic Information Technology Services provides First-Aid and
general consulting services to those who use Unix computing systems on
campus. aITs Unix machines run the Ultrix version of Unix. With the
realization that there are other versions of Unix being used on
campus, First-Aid and the aITs Help Desk will address questions based
on their experience with the aITs Unix systems.
Students should use the First-Aid service (located in all WAM
workstation laboratories). They may also use the First-Aid Hotline
for phone-in questions ((301) 405-6941), which is answered by
First-Aiders in the PGII WAM lab.
Exact hours of service are posted at each First-Aid station.
The aITs Information Technology Library (CSS West Wing room 1400) has
reference copies of Unix manuals and documentation. The Library also
sells "Introduction to the aITs UNIX Systems" (aITs Unix handout
number 1).
News
Academic Information Technology Services uses the Usenet news
system on its Unix systems to inform users about system outages, new
software, etc. The news group csc.news is used for all news items.
Items that are considered of interest to the general University
community are also placed in the um.general news group.
The default .login file contains a call to the readnews program.
On some systems, users prefer to use the rn program to read news. If
rn is used, the call to readnews should be removed from the users'
.login file.
Printing
aITs has replaced the stock lpr program with a shell script that
calls MDQS to print a file on prl, which is the 3800 laser printer
attached to the campus UMDD IBM system.
The call is
lpr <file>
to initiate printing.
Output may be retrieved at the aITs dispatch counter on the first
floor of the CSS building.
File Recovery
A dump of all files is taken every week. These file backups are for
recovery from catastrophic loss. Individual user file recovery is not
available at this time.
Passwords
Unix systems do not have the concept of an account manager; this means
that if a user forgets his password, aITs must change it for the user.
Requests for change of password should be made to Ira Gold at the
address above. Requests to change student passwords will only be
honored when they are made by the instructor. Instructors can make
such requests via electronic mail. Requests must include login id and
may include a suggested new password.
Disk Quota
All user login ids on the aITs Unix systems have a disk quota
associated with them. When the disk quota is exceeded, the user will
not be able to create new files until the amount of disk space in use
has been reduced, or the disk quota has been increased.
Requests for change of disk quota should be made to Ira Gold at the
address above. Requests to change student disk quotas will only be
honored when they are made by the instructor. Instructors can make
such requests via electronic mail. Requests must include login id,
desired new disk quota (expressed in megabytes), and system name. In
all cases, requests for higher disk quotas will be evaluated against
system resources and system load.
/tmp and /var/tmp
/tmp is a small directory used by system utilities for short term
scratch files. Users should not place their files in /tmp. User
files should be placed in user directories (every user has one) or
/var/tmp (again, short term storage).
Files residing in /tmp and /var/tmp can be deleted without notice if
disk space becomes critical. See "Disk Quota" above for information
about requesting disk quota changes.
/tmp and /var/tmp are local to each system in the cluster.
Software
The cluster file /usr/local/doc/cluster contains cluster details,
including a table showing software availability. Please read this
file for full cluster details.
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