Setting Terminal Characteristics



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Setting Terminal Characteristics

In contrast to proprietary systems like DEC's VMS or IBM's VM, Unix was written so that users may use terminals from any vendor. That being the case, for Unix to properly format output to your screen, the system must know your terminal's characteristic quirks. You tell Unix what kind of terminal you are using by setting the environmental variable TERM to a name corresponding to your terminal type. If the setting is improper, you may see:       

% vi .cshrc   	Let's edit the .cshrc file.   
Unknown terminal type - all I have is 'dumb' [Using open mode]   	   

With an incorrectly set terminal, editors and listing commands will act incorrectly. For example, editors may have problems adding new lines, and pagers may not scroll properly.

To set your terminal type, you set the environmental variable TERM. In sh or ksh this is done with export, in csh with setenv :

% echo $TERM   	Tell me present terminal setting.   
dumb   	Don't take this personally.   
ksh$ export TERM=ansi   	A popular generic terminal.   
csh% setenv TERM ansi   	A popular generic terminal (csh).   


TERMINAL TYPES
ansi
Popular generic type based on vt100;
a good choice if you don't know better.
vt100
Actually a DEC terminal adopted as generic.
xterm
An X Window System terminal.
dumb
System default for unknown terminal.
unknown
Another default for unknown terminal.

More specific terminal characteristics are reported and set with the stty command. There are BSD and POSIX versions:

% stty   	No options, show characteristics.   
speed 9600 baud; evenp hupcl clocal   	The characteristics.   
brkint -inpck -istrip icrnl -ixany   	    
% stty everything    	Display everything, -a for System V.   
% Ctrl-J stty sane Ctrl-J   	Reset terminal  after being messed up.   

Once you have the terminal characteristics which you like and which work for you, you can put them in your .login file and not worry about it again. To learn more about stty and its options, refer to the man pages.



next up previous contents index
Next: Abbreviations with Aliases Up: Personalizing Unix Previous: Environmental Variables