|
If a user on a Unix machine has problems with his or her
terminal settings, in such a way that full screen programs do
not work or the backspace key just puts either ^H or
^? on
the screen, then their terminal type, screen size or erase
key needs to be set. Terminal type information is kept in the
environment space and as a shell variable (meaning it will
only affect that shell if you change it). The backspace key
and screen size are part of the ioctl information for the
tty. (If you don't know what that is: man -k ioctl.)
The most common cause of problems is the user typed in the
wrong terminal type when the .login file asked for it (tset
-s -m ':?'), although if the user tries to make a smart
.login file which senses where he or she is coming from (via
the $term shell variable) it could get set incorrectly there
as well. You can use printenv to find out what the values of
the term and termcap variables.
Setting Terminal
Type
The proper terminal types for the labs are:
PS/2: vt200; Macintosh: vt100; NeXT: vt100; A Good Guess if
you aren't sure where they're coming from and neither are
they: vt100
To fix it, you can either source .login and enter the
correct information, or manually set it with "set noglob;
eval `tset -s -m 'termtype'`". Doing a "set
term=termtype; tset" will usually work as well.
If the Terminal Type is Set Correctly/Resizing the
Screen
If the terminal type is set correctly, but the screen size
isn't then use "eval `resize`" to automatically set the
screen size. Unfortunately, some terminal emulations do not
properly process these sequences and the screen size gets set
to one column by 24 rows or something worse. Another frequent
problem is some Unix programs supply a linefeed at the last
column of the screen and the local terminal program also
supplies one. When this happens the user sees an extra blank
line and finds that none of the lines below this match where
the system thinks they are in vi. One solution to fix any of
the problems in this paragraph is to manually set the rows
and columns using the stty command. The exact sequence is
stty rows #rows columns #columns
In the case of resize not working just set it to the correct
size.
One way to fix the double linefeed problem with vi is to tell
the system you have one or two less columns that you actually
do.
Setting the
Backspace Key
For the backspace key, it isn't quite as easy. The problem
here is that there are two common backspace codes: backspace
and delete. One is ^H, the other is ^?. If you are having
problems it is because your terminal program choose the one
the system didn't. The default cluster login scripts set it
to ^H. One solution is to change the setting in the local
terminal emulator. However there are many possible emulators
and we can't support them all. So, to fix this on the Unix
side, you have to type the following at the shell prompt:
stty erase ^v<press backspace key right after
typing ^v>
The ^v (control - v ) is the "quote character." It keeps the
shell from interpreting the next keystroke. This is necessary
because some shells are smart enough to realize that either
^H or ^? should be treated as the backspace character, but
some programs don't (like mail, vi...).
|
