NAME
tset,
reset —
terminal initialization
SYNOPSIS
tset |
[-IQrs]
[-]
[-e ch]
[-i ch]
[-k ch]
[-m
mapping]
[terminal] |
reset |
[-IQrs]
[-]
[-e ch]
[-i ch]
[-k ch]
[-m
mapping]
[terminal] |
DESCRIPTION
tset initializes terminals.
tset first
determines the type of terminal that you are using. This determination is done
as follows, using the first terminal type found.
- The
terminal argument specified on the command
line.
- The value of the
TERM
environmental variable.
- The terminal type associated
with the standard error output device in the /etc/ttys
file.
- The default terminal type,
“unknown”.
If the terminal type was not specified on the command-line, the
-m option mappings are then applied (see below for more
information). Then, if the terminal type begins with a question mark (``?''),
the user is prompted for confirmation of the terminal type. An empty response
confirms the type, or, another type can be entered to specify a new type. Once
the terminal type has been determined, the terminfo entry for the terminal is
retrieved. If no terminfo entry is found for the type, the user is prompted
for another terminal type.
Once the terminfo entry is retrieved, the window size, backspace, interrupt and
line kill characters (among many other things) are set and the terminal and
tab initialization strings are sent to the standard error output. Finally, if
the erase, interrupt and line kill characters have changed, or are not set to
their default values, their values are displayed to the standard error output.
When invoked as
reset,
tset sets cooked and
echo modes, turns off cbreak and raw modes, turns on newline translation and
resets any unset special characters to their default values before doing the
terminal initialization described above. This is useful after a program dies
leaving a terminal in a abnormal state. Note, you may have to type
“
<LF>reset<LF>
” (the line-feed
character is normally control-J) to get the terminal to work, as
carriage-return may no longer work in the abnormal state. Also, the terminal
will often not echo the command.
The options are as follows:
-
-
- -
- The terminal type is displayed to the standard output, and
the terminal is not initialized in any way.
-
-
- -e
- Set the erase character to ch.
-
-
- -I
- Do not send the terminal or tab initialization strings to
the terminal.
-
-
- -i
- Set the interrupt character to
ch.
-
-
- -k
- Set the line kill character to
ch.
-
-
- -m
- Specify a mapping from a port type to a terminal. See below
for more information.
-
-
- -Q
- Don't display any values for the erase, interrupt and line
kill characters.
-
-
- -r
- Print the terminal type to the standard error output.
-
-
- -s
- Print the sequence of shell commands to initialize the
environment variable
TERM
to the standard output.
See the section below on setting the environment for details.
The arguments for the
-e,
-i and
-k options may either be entered as actual characters or by
using the “hat” notation, i.e. control-h may be specified as
“
^H
” or
“
^h
”.
SETTING THE ENVIRONMENT
It is often desirable to enter the terminal type and information about the
terminal's capabilities into the shell's environment. This is done using the
-s option.
When the
-s option is specified, the commands to enter the
information into the shell's environment are written to the standard output.
If the
SHELL
environmental variable ends in
“csh”, the commands are for the
csh(1), otherwise, they are for
sh(1). Note, the
csh(1) commands
set and
unset the shell variable
“noglob”, leaving it unset. The following line in the
.login or
.profile files will initialize
the environment correctly:
eval `tset -s options ... `
To demonstrate a simple use of the
-S option, the following
lines in the
.login file have an equivalent effect:
set noglob
set term=(`tset -S options ...`)
setenv TERM $term[1]
unset term
unset noglob
TERMINAL TYPE MAPPING
When the terminal is not hardwired into the system (or the current system
information is incorrect) the terminal type derived from the
/etc/ttys file or the
TERM
environmental variable is often something generic like “network”,
“dialup”, or “unknown”. When
tset is
used in a startup script (
.profile for
sh(1) users or
.login for
csh(1)
users) it is often desirable to provide information about the type of terminal
used on such ports. The purpose of the
-m option is to
“map” from some set of conditions to a terminal type, that is, to
tell
tset ``If I'm on this port at a particular speed, guess
that I'm on that kind of terminal''.
The argument to the
-m option consists of an optional port
type, an optional operator, an optional baud rate specification, an optional
colon (``:'') character and a terminal type. The port type is a string
(delimited by either the operator or the colon character). The operator may be
any combination of: “
>
”,
“
<
”,
“
@
”, and
“
!
”;
“
>
” means greater than,
“
<
” means less than,
“
@
” means equal to and
“
!
” inverts the sense of the test. The
baud rate is specified as a number and is compared with the speed of the
standard error output (which should be the control terminal). The terminal
type is a string.
If the terminal type is not specified on the command line, the
-m mappings are applied to the terminal type. If the port
type and baud rate match the mapping, the terminal type specified in the
mapping replaces the current type. If more than one mapping is specified, the
first applicable mapping is used.
For example, consider the following mapping:
“
dialup>9600:vt100
”. The port type is
“
dialup
”, the operator is
“
>
”, the baud rate specification is
“
9600
”, and the terminal type is
“
vt100
”. The result of this mapping is to
specify that if the terminal type is
“
dialup
”, and the baud rate is greater
than 9600 baud, a terminal type of “
vt100
”
will be used.
If no port type is specified, the terminal type will match any port type, for
example, “
-m dialup:vt100 -m :?xterm
” will
cause any dialup port, regardless of baud rate, to match the terminal type
“
vt100
”, and any non-dialup port type to
match the terminal type “
?xterm
”. Note,
because of the leading question mark, the user will be queried on a default
port as to whether they are actually using an
xterm
terminal.
No whitespace characters are permitted in the
-m option
argument. Also, to avoid problems with metacharacters, it is suggested that
the entire
-m option argument be placed within single quote
characters, and that
csh(1) users
insert a backslash character (``\'') before any exclamation marks (``!'').
ENVIRONMENT
The
tset command uses the
SHELL
and
TERM
environment variables.
FILES
- /etc/ttys
- system port name to terminal type mapping database
- /usr/share/misc/terminfo
- terminal capability database
COMPATIBILITY
The
-A,
-E,
-h,
-u and
-v options have been deleted from
the
tset utility. None of them were documented in
4.3BSD and all are of limited utility at best. The
-a,
-d and
-p options
are similarly not documented or useful, but were retained as they appear to be
in widespread use. It is strongly recommended that any usage of these three
options be changed to use the
-m option instead. The
-n option remains, but has no effect. It is still
permissible to specify the
-e,
-i and
-k options without arguments, although it is strongly
recommended that such usage be fixed to explicitly specify the character.
Executing
tset as
reset no longer implies
the
-Q option. Also, the interaction between the
- option and the
terminal argument in
some historic implementations of
tset has been removed.
The
-E and
-S options have been removed as
they only make sense for termcap and
tset now uses terminfo.
As such, the
TERMCAP
entry has been removed from
-s.
Finally, the
tset implementation has been completely redone
(as part of the addition to the system of a
IEEE Std
1003.1-1988 (“POSIX.1”) compliant terminal interface) and
will no longer compile on systems with older terminal interfaces.
SEE ALSO
csh(1),
sh(1),
stty(1),
tty(4),
terminfo(5),
ttys(5),
environ(7)
HISTORY
The
reset and
tset commands appeared in
1BSD.