Simtel MSDOS - Coast to Coast/simteldosarchivecoasttocoast2.iso/ncsatlnt/tel23doc.zip/CHAP.3

Text File | 1991-07-01 | 14KB | 373 lines

3.1    NCSA Telnet


More About Managing Sessions    3.1


National Center for Supercomputing Applications


June 1991






3.1    NCSA Telnet

More About Managing Sessions    3.1

National Center for Supercomputing Applications

June 1991



6/30/91




Chapter 3    More About Managing Sessions



Chapter Overview
Keyboard Commands
Using the Skip Command (ALT-S)
Resetting the VT100 Screen (ALT-R)
Aborting the Program (CTRL-SHIFT-F3)
Escaping to DOS Shell (ALT-E)
Parameter Menu
Using Screen Text Colors
Using Remote Echo and Local Echo
Using the Backspace Key
Changing the Session Name
Changing the Terminal Type
Using Line Wrapping
Using Output Mapping
Changing the Capture Filename
Using Screen Mode
Using File Transfer Mode
Using Clock Mode

Chapter Overview

This chapter continues the discussion of multiple sessions and
describes more advanced aspects of the NCSA Telnet working
environment. The chapter explains how to reset the VT100 screen,
how to abort NCSA Telnet, the DOS shell feature, and the
Parameters menu options.


Keyboard Commands

Using the Skip Command
(ALT-S)
The skip command causes the screen to "skip ahead" over
scrolling text. The text is placed into the scrollback region, but the
screen update advances to the end of the local network buffer
instead of printing every line on the screen. This feature is useful
for quickly bypassing seemingly endless lines of output from
certain commands. To use the command, press ALT-S and the
screen will pause, then redraw at the end of the local buffer. ALT-S
won't solve all of the network buffering problems for interactive
use, but it should help. Capture to disk and scrollback commands
are not affected by the skip command.


Resetting the VT100 Screen
(ALT-R)
ALT-R clears and resets all modes associated with the current
virtual VT100 screen. Some host programs can accidentally set
graphics mode on or fail to leave graphics mode. By pressing
ALT-R, NCSA Telnet will override all VT100 mode settings
including the following:  turning off wrap mode, resetting
graphics mode, setting the keypad mode back to the default, and
resetting tabs to every eight spaces. After using ALT-R, you may
wish to set your terminal type again to allow the host to reset
whatever VT100 modes it needs.


Aborting the Program
(CTRL-SHIFT-F3)
If for some reason none of the current connections respond,
SCROLL LOCK is not on, and ALT-R and ALT-X do not appear to
have any effect, CTRL-SHIFT-F3 is a general abort command that
exits NCSA Telnet and returns you to DOS. If you do abort NCSA
Telnet with CTRL-SHIFT-F3, NCSA Telnet cannot notify the
host(s) that your session(s) are terminated. Your sessions are left
in an undetermined state. This situation can cause a variety of
problems for the host, because it cannot immediately determine
that the session has ended. For example, the programs may
continue to run on the host, even though you exited NCSA Telnet
with CTRL-SHIFT-F3.


Escaping to DOS Shell
(ALT-E)
Pressing ALT-E to escape to DOS preserves your connections while
you use the DOS command shell. You may use most DOS
commands and programs, including those which look at
directories, edit source files, or even compile programs. To return
to NCSA Telnet, you must enter the command exit at the DOS
prompt.
During the escape to DOS, NCSA Telnet monitors the Ethernet for
incoming packets every one-half second. If you run other
programs which affect the Ethernet or the timer which NCSA
Telnet uses, your connections may be lost╤or worse╤your
computer may crash. The following programs are examples of
those which terminate the network handling of NCSA Telnet,
causing connections to be lost or DOS to crash:

Ñ    SideKick (it turns off timer processes, so it can cause lost
connections)

Ñ    All network programs (they reset the Ethernet board)

Ñ    NCSA Telnet (it is a network program)

Ñ    User FTP (it, too, is a network program)

Ñ    format, the DOS format utility for floppy disks

Ñ    FileCommand II

NOTE: Watch memory usage to prevent crashing. Also,
remember to exit DOS when you have finished your DOS activities.

Parameter Menu

Press ALT-P to display the Parameter menu options, which appear
on the screen as shown in Figure 3.1. These options control the
settings for text color, echo mode, backspace key, session name,
terminal type, capture file name, screen mode and file transfer
mode. You can change the fields that are shown in bold to different
values.

Figure 3.1    Parameter Menu

ALT-P                         Parameter menu
   <      Select parameters, F1 to accept, F10 to leave unchanged      >

   --------------- Color setup and session parameters -----------------
 Text:         normal    reverse   underline
    Normal Foreground (nfcolor)    -    green
    Normal Background (nbcolor)    -    black
    Reverse Foreground (rfcolor)    -    black
    Reverse Background (rbcolor)    -    white
    Underline Foreground (ufcolor)    -    blue
    Underline Background (ubcolor)    -    black
    Use remote echo or local echo    -    Remote echo
    Backspace key sends    -    Delete
    Session name    *>    ahostname
    Terminal type    -    VT102 and Tek4014
    Line Wrapping    -    Wrapping On
    Output Mapping    -    Mapping Off
   -------------- Parameters which apply to all sessions --------------
    Capture file name    *>    capfile
  Screen mode (for BIOS compatibility)    Direct to screen
    File transfer is    -    Enabled
    Remote Copying is    -    Enabled
    Clock is     Enabled


Use arrow keys to select, Enter clears changeable field (*>)


The up arrow, down arrow, HOME, and END keys allow you to
move the cursor from option to option. The left and right arrow
keys rotate through the allowed settings for each option. For each
field that you wish to change, move the cursor to that field and press
the left or right arrow until the desired value appears. After
changing all of the fields that you wish to change, press the F1 key
to return to your session with the changes in effect. If you make a
mistake, or decide that no changes are necessary, press ESC to
return to your session without any changes taking place.

There are two special fields, marked with the symbol *>, to
indicate that the present value may be changed by typing another.
To change one of these, place the cursor on top of the changeable
field and then press RETURN. The program blanks the field and
allows you to enter a new value. Press RETURN when you are
finished entering the new value. After you enter a new value, but
before you press F1, the old value still remains in memory and you
may use the left or right arrow keys to regain the old value.

Following are descriptions of the parameters you can set.


Using Screen Text Colors
Host programs expect to be able to control the attributes of
characters on the VT100 screen. Command codes are sent to your
PC to display characters in normal, reverse, underlined,
blinking, and bold attributes, or combinations of these. When
normal, reverse, and underline text are required, you have control
over which colors are used. When blink or bold attributes are
required, NCSA Telnet adds them to your selected colors.

For normal, reverse, and underlined characters, NCSA Telnet
gives you your choice of foreground and background colors, a total
of six settings. The color choices for a PC color video display are
black, blue, green, cyan, red, magenta, yellow, and white. The
foreground color command allows bright versions of these colors,
while the background color command allows users to set blinking
as an attribute. For each of the text modes, normal, reverse, and
underlined, use the Parameter menu to select the foreground and
background colors. As you change the selections, the sample text
on the fourth line of the screen provides an example of how the text
will appear in the VT100 emulation.

On monochrome screens, when you display a character in the color
blue, the PC produces a visible underline on the screen instead of
blue coloring.

Color screens do not have the visible underline capability and use
a visible blue color instead of underlining.

Bold and blinking attributes from the VT100 screen appear as bold
and blinking characters on the PC screen.


Using Remote Echo and
Local Echo
When the response time of the network is long (such as with
satellite transmission), you may want to buffer your keyboard
input locally, only sending characters to the host when you press
RETURN. This action is often referred to as a line mode or local
echo mode. The alternative to line mode is called character mode
or remote echo mode, where the local program immediately sends,
and remote host echoes, every character over the network.

In local echo mode, NCSA Telnet  buffers most characters typed at
the keyboard until you press RETURN, which sends the characters
to the host all in one packet. There are some exceptions to this rule.

Ñ    CTRL-U erases the local buffer.

Ñ    Backspace (CTRL-H) erases the most recent character added to
the local buffer.

Ñ    Tab (CTRL-I) forces NCSA Telnet to send the local buffer (with
the tab).

Ñ    All other control characters echo with a caret (e.g., ^A) and
force NCSA Telnet to send the local buffer with the control
character included.
Ñ    Arrow keys and all other unprintable ASCII characters, the
escape character for example, force NCSA Telnet to send the
local buffer, with the character included.

Ñ    You cannot send a CTRL-U or Backspace to the host in line
mode.

Ñ    ALT keys and other local command keys are not affected by
local echo mode.

NOTE: For full screen editing, character mode (remote echo) is
necessary, so most hosts use this mode. When full screen editing
is not required, line mode may be more efficient.


Using the Backspace Key
NCSA Telnet automatically translates BACKSPACE keypresses
into DELETE codes, for compatibility with systems that prefer the
use of DELETE to BACKSPACE. If you find that your backspaces
are not being accepted, the host you are connected to may prefer the
reverse setting. To test this possibility, use the Parameter menu to
change the default translation so the BACKSPACE key functions
as backspace. If the result is that your backspaces are accepted,
then the host does prefer the BACKSPACE to DELETE. If you
require the reverse setting frequently, you or your system
administrator may want to permanently reset the backspace
function using the configuration file, as described in Chapter 7,
"Installation and Configuration."


Changing the Session
Name
The status line shows a 13-character session name for each active
session in the lower right-hand corner. For each session, the
machine name that you typed to initiate the first session displays
as the default name for successive sessions. The Parameter menu
allows you to change the status line name for the current session.
Press RETURN to clear the current entry and type in a new name.
Only the first 13 characters are used.


Changing the Terminal
Type
Generally, the default terminal type of VT100 with Tektronix 4014
is acceptable. Because specific cases may exist where you need to
force some restrictions on the way the terminal acts, you may want
to limit the amount of emulation that NCSA Telnet does. The three
choices of terminal types are:

Ñ    VT100 terminal with Tektronix 4014 graphics

Ñ    VT100 only╤graphics commands ignored, but VT100
commands accepted

Ñ    Dumb terminal╤no VT100 codes or Tektronix codes
interpreted


Using Line Wrapping
If you enable the line wrapping feature, the text wraps when it
reaches the end of a line. Otherwise, the text piles up at the end of
the line.


Using Output Mapping
The output mapping function allows you to translate characters
from the host machine as the screen displays them. This function
is similar to keyboard mapping, except that keyboard mapping
works in reverse.


Changing the Capture
Filename
You can change the name of the current capture file in the
Parameter menu. Press RETURN to clear the current entry and
then enter your new filename. After changing the name of the
capture file, all subsequent ALT-C commands use the new capture
file. You can also change the name of the capture file
"permanently" in the configuration file (see Chapter 7,
"Installation and Configuration."). See Chapter 2, "Introduction
to Managing Sessions," for a description of capture file operations.


Using Screen Mode (BIOS
Compatibility for
Windowing Packages)
In the normal fast mode, writes are made directly to the screen for
increased speed; however, this mode is incompatible with
windowing packages like Topview or Microsoft Windows and
may cause snow on some screens. To avoid small problems,
developers have created a compatibility mode within NCSA Telnet
where IBM's BIOS calls are used for all access to the screen.

Usually, the windowing compatibility mode is set up in the
configuration file with the bios option. However, if a change is
needed once you are in the program, the Parameter menu option is
available.


Using File Transfer Mode
NCSA Telnet separates the file transfer mode into an option for
File Transfer Protocol (FTP) and an option for rcp. The
Parameter menu allows you to disable or enable file transfers.
When you select Disabled, neither FTP nor rcp is allowed. When
you select Enabled, the FTP and rcp servers are restarted. Chapter
5, "File Transfer," contains more information on the file transfer
methods for NCSA Telnet. You or your system administrator can
set the default file transfer modes for FTP and rcp in the
configuration file (see Chapter 7, "Installation and
Configuration.").


Using Clock Mode
When you enable the clock mode option, NCSA Telnet displays a
digital clock in the corner of the screen.