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Copyright CourseWare Technologies Inc. 1988-88
Lesson - 8
BASIC COMMUNICATIONS
MENU
Basic Communications|Topics to Learn|8-0|9,56
# Topic
--- -------
1 - Introduction
2 - Using the Local Mail Facility
3 - Inter-System Mail
4 - Communication Using cu
5 - Other Communication Facilities
6 - Lesson Review
0 - Exit This Session
P1
Basic Communications|Introduction|8-1.1|12,51
There are several means and advanced network
facilities available for communication on UNIX systems.
The first utility for communication between users on
the same and different systems is:
mail
mail, like many other utilities for communication
between users on various systems, is a part of the
UUCP family of commands. (UUCP stands for UNIX to
UNIX CoPy.)
P2
Basic Communications|Introduction|8-1.2|6,51
The rest of this lesson will discuss in detail
the usage of:
* mail,
* uucp, and
* cu.
P3
Basic Communications|Using the Local Mail Facility|8-2.1|7,54
The standard UNIX facility for communication
between users on the same system is mail.
mail sends the message to the user with the
specified login name. The mail message can be entered
from the standard input or redirected from a file.
P4
Basic Communications|Using the Local Mail Facility|8-2.2|7,50
mail can be used for sending/writing mail and
for receiving/reading mail.
The mail message is placed in the directory
/usr/spool/mail/login name or the directory defined
by the MAIL environment variable!
P5
Basic Communications|Inter-System Mail|8-3.1|14,53
UNIX provides you with a capability to send
mail to the users on other systems with almost
identical ease as that for the host system. The
only difference is that you have to add the remote
site name followed by ! (\! under C-Shell).
For example, if the site name was dual and
the user's name was yori, then to send mail to
the user yori on the remote system dual you would
type:
mail dual!yori (Bourne Shell)
mail dual\!yori (C-Shell)
P6
Basic Communications|Inter-System Mail|8-3.2|3,50
The command that lets you determine which
remote systems your system knows about is uuname,
the UUCP name for known systems.
P7
Basic Communications|Inter-System Mail|8-3.3|13,54
You can send mail to the systems not in the
uuname list as long as the forwarding system in
the uuname list knows about them. If uuname on
your system produced:
dual
durango
cti
then you could send this mail message:
mail cti!wytec!johns
as long as the system cti knows about the system
wytec!
P8
Basic Communications|Communication Using cu|8-4.1|7,56
cu - call up another UNIX system - is a useful
and easy-to-use command for calling a remote UNIX
system via modem, executing commands on the remote
UNIX system and transferring small text files between
the systems. cu lets you perform all of the above
activities while you're still logged on to the host
UNIX system.
P9
Basic Communications|Communication Using cu|8-4.2|5,56
The default speed and call-out device for cu
is specified in the file /usr/lib/uucp/L-devices.
The maximum speed for telephone cu connection is
limited to the slowest modem speed, while for the
direct connection it is up to 9600 baud.
P10
Basic Communications|Communication Using cu|8-4.3|11,50
To improve the success in cu communication,
you need to make sure that there is an appropriate
mapping of carriage-returns to carriage-returns and
of line-feeds to line-feeds. A command to help you
do this is:
~!stty nl tabs < calling_device
Also make sure that the kill character is
identical on the host and the remote systems.
P11
Basic Communications|Communication Using cu|8-4.4|15,44
Remember, to copy the file admin from the
remote system to the host system use:
~%take admin
To copy the file concepts from the host
system to the remote system use:
~%put concepts
NOTE: Both put and take are executed
while you are on the remote system.
P12
Basic Communications|Other Communication Facilities|8-5.1|8,54
Other communication facilities include:
* communication through the UUCP command family
* communication through RFS/NFS software
Details for these facilities are given in the
Advanced System Administrator tutorial.
P13
Basic Communications|Other Communication Facilities|8-5.2|14,55
UUCP commands permit one to execute commands and
send data and between computer systems connected by a
serial link and or a telephone line.
In order to communicate, the software on the systems
on a network must be configured so that the systems
recognize one another.
UUCP commands permit data transfers of up to 9600
baud. The syntax for the uucp command is:
uucp source-file destination
P14
Basic Communications|Other Communication Facilities|8-5.3|14,60
RFS permits transfers of up to 10 Mbits per second.
The systems must be connected through a local area
network (LAN) with special LAN hardware.
The syntax for file transfers from a remote system
to your current system is:
rcp remote-system:file newfile
The syntax for file transfers from your current
system to a remote system is:
rcp file-on-current-system remote-system:newfile