- 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.
+
+ This program initializes terminals.
+
+ First, tset retrieves the current terminal mode settings
+ for your terminal. It does this by successively testing
+
+ o the standard error,
+
+ o standard output,
+
+ o standard input and
+
+ o ultimately "/dev/tty"
+
+ to obtain terminal settings. Having retrieved these set-
+ tings, tset remembers which file descriptor to use when
+ updating settings.
+
+ Next, tset determines the type of terminal that you are
+ using. This determination is done as follows, using the
+ first terminal type found.
1. The terminal argument specified on the command line.
2. The value of the TERM environmental variable.
- 3. (BSD systems only.) The terminal type associated with
- the standard error output device in the /etc/ttys file.
- (On Linux and System-V-like UNIXes, getty does this job by
- setting TERM according to the type passed to it by
- /etc/inittab.)
+ 3. (BSD systems only.) The terminal type associated with
+ the standard error output device in the /etc/ttys file.
+ (On System-V-like UNIXes and systems using that conven-
+ tion, getty does this job by setting TERM according to the
+ type passed to it by /etc/inittab.)
- 4. The default terminal type, ``unknown''.
+ 4. The default terminal type, "unknown".
- If the terminal type was not specified on the command-
- line, the -m option mappings are then applied (see the
+ If the terminal type was not specified on the command-
+ line, the -m option mappings are then applied (see the
section TERMINALTYPEMAPPING for more information).
- Then, if the terminal type begins with a question mark
- (``?''), the user is prompted for confirmation of the ter-
- minal 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 ter-
+ Then, if the terminal type begins with a question mark
+ ("?"), the user is prompted for confirmation of the termi-
+ nal 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 ter-
minal type.
- Once the terminfo entry is retrieved, the window size,
- backspace, interrupt and line kill characters (among many
+ 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 initializa-
- tion 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.
- Use the -c or -w option to select only the window sizing
- versus the other initialization. If neither option is
- given, both are assumed.
+ tion 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 transla-
tion and resets any unset special characters to their
@@ -107,17 +122,20 @@
leaving a terminal in an abnormal state. Note, you may
have to type
- <LF>reset<LF>
+ <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:
- -c Set control characters and modes. -e Set the erase
- character to ch.
+ -c Set control characters and modes.
+
+ -e Set the erase character to ch.
-I Do not send the terminal or tab initialization
strings to the terminal.
@@ -126,39 +144,40 @@
-k Set the line kill character to ch.
- -m Specify a mapping from a port type to a terminal.
+ -m Specify a mapping from a port type to a terminal.
See the section TERMINALTYPEMAPPING for more infor-
mation.
- -Q Do not display any values for the erase, interrupt
+ -Q Do not display any values for the erase, interrupt
and line kill characters. Normally tset displays the
- values for control characters which differ from the
+ values for control characters which differ from the
system's default values.
- -q The terminal type is displayed to the standard out-
- put, and the terminal is not initialized in any way.
- The option `-' by itself is equivalent but archaic.
+ -q The terminal type is displayed to the standard out-
+ put, and the terminal is not initialized in any way.
+ The option "-" by itself is equivalent but archaic.
-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 SETTINGTHEENVIRONMENT for details.
+ See the section SETTINGTHEENVIRONMENT for details.
-V reports the version of ncurses which was used in this
program, and exits.
- -w Resize the window to match the size deduced via
+ -w Resize the window to match the size deduced via
setupterm. Normally this has no effect, unless
setupterm is not able to detect the window size.
The arguments for the -e, -i, and -k options may either be
- entered as actual characters or by using the `hat' nota-
- tion, i.e. control-h may be specified as ``^H'' or ``^h''.
+ entered as actual characters or by using the "hat" nota-
+ tion, i.e., control-h may be specified as "^H" or "^h".
+ If neither -c or -w is given, both options are assumed.
-
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.
@@ -166,7 +185,7 @@
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 csh, otherwise, they
+ ends in "csh", the commands are for csh, otherwise, they
are for sh. Note, the csh commands set and unset the
shell variable noglob, leaving it unset. The following
line in the .login or .profile files will initialize the
@@ -175,8 +194,7 @@
eval `tset -s options ... `
-
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
@@ -185,22 +203,22 @@
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 -m options maps from some set of conditions to a ter-
+ minal type, that is, to tell tset "If I'm on this port at
+ a particular speed, guess that I'm on that kind of termi-
+ nal".
The argument to the -m option consists of an optional port
type, an optional operator, an optional baud rate specifi-
- cation, an optional colon (``:'') character and a terminal
+ cation, 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.
+ 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
@@ -231,36 +249,58 @@
argument. Also, to avoid problems with meta-characters,
it is suggested that the entire -m option argument be
placed within single quote characters, and that csh users
- insert a backslash character (``\'') before any exclama-
- tion marks (``!'').
+ insert a backslash character ("\") before any exclamation
+ marks ("!").
-
-
HISTORY
- The tset command appeared in BSD 3.0. The ncurses imple-
- mentation was lightly adapted from the 4.4BSD sources for
- a terminfo environment by Eric S. Raymond <esr@snark.thyr-
- sus.com>.
+
+ A reset command appeared in 2BSD (1979), written by Kurt
+ Shoens.
+ A separate tset command was provided in 2BSD by Eric All-
+ man. While the oldest published source (from 1979) pro-
+ vides both programs, Allman's comments in the 2BSD source
+ code indicate that he began work in October 1977, continu-
+ ing development over the next few years.
-
-
COMPATIBILITY
- The tset utility has been provided for backward-compati-
- bility with BSD environments (under most modern UNIXes,
- /etc/inittab and getty(1) can set TERM appropriately for
- each dial-up line; this obviates what was tset's most
- important use). This implementation behaves like 4.4BSD
- tset, with a few exceptions specified here.
-
- The -S option of BSD tset no longer works; it prints an
- error message to stderr and dies. The -s option only sets
- TERM, not TERMCAP. Both these changes are because the
- TERMCAP variable is no longer supported under terminfo-
- based ncurses, which makes tset-S useless (we made it die
- noisily rather than silently induce lossage).
+ In 1980, Eric Allman modified tset to provide a "reset"
+ feature when the program was invoked as reset.
+
+ The ncurses implementation was lightly adapted from the
+ 4.4BSD sources for a terminfo environment by Eric S. Ray-
+ mond <esr@snark.thyrsus.com>.
+
+
+
+ Neither IEEE Std 1003.1/The Open Group Base Specifications
+ Issue 7 (POSIX.1-2008) nor X/Open Curses Issue 7 documents
+ tset or reset.
+
+ The AT&T tput utility (AIX, HPUX, Solaris) incorporated
+ the terminal-mode manipulation as well as termcap-based
+ features such as resetting tabstops from tset in BSD
+ (4.1c), presumably with the intention of making tset obso-
+ lete. However, each of those systems still provides tset.
+ In fact, the commonly-used reset utility is always an
+ alias for tset.
+
+ The tset utility provides for backward-compatibility with
+ BSD environments (under most modern UNIXes, /etc/inittab
+ and getty(1) can set TERM appropriately for each dial-up
+ line; this obviates what was tset's most important use).
+ This implementation behaves like 4.4BSD tset, with a few
+ exceptions specified here.
+
+ A few options are different because the TERMCAP variable
+ is no longer supported under terminfo-based ncurses:
+
+ o The -S option of BSD tset no longer works; it prints
+ an error message to the standard error and dies.
+
+ o The -s option only sets TERM, not TERMCAP.
There was an undocumented 4.4BSD feature that invoking
- tset via a link named `TSET` (or via any other name begin-
+ tset via a link named "TSET" (or via any other name begin-
ning with an upper-case letter) set the terminal to use
upper-case only. This feature has been omitted.
@@ -270,23 +310,54 @@
-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. The -adnp options are
- therefore omitted from the usage summary above.
-
- It is still permissible to specify the -e, -i, and -k
- options without arguments, although it is strongly recom-
- mended that such usage be fixed to explicitly specify the
+ options be changed to use the -m option instead. The -a,
+ -d, and -p options are therefore omitted from the usage
+ summary above.
+
+ Very old systems, e.g., 3BSD, used a different terminal
+ driver which was replaced in 4BSD in the early 1980s. To
+ accommodate these older systems, the 4BSD tset provided a
+ -n option to specify that the new terminal driver should
+ be used. This implementation does not provide that
+ choice.
+
+ It is still permissible to specify the -e, -i, and -k
+ options without arguments, although it is strongly recom-
+ mended that such usage be fixed to explicitly specify the
character.
- As of 4.4BSD, executing tset as reset no longer implies
+ As of 4.4BSD, 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.
-
-
-
ENVIRONMENT
+ The -c and -w options are not found in earlier implementa-
+ tions. However, a different window size-change feature
+ was provided in 4.4BSD.
+
+ o In 4.4BSD, tset uses the window size from the termcap
+ description to set the window size if tset is not able
+ to obtain the window size from the operating system.
+
+ o In ncurses, tset obtains the window size using
+ setupterm, which may be from the operating system, the
+ LINES and COLUMNS environment variables or the termi-
+ nal description.
+
+ Obtaining the window size from the terminal description is
+ common to both implementations, but considered obsoles-
+ cent. Its only practical use is for hardware terminals.
+ Generally speaking, a window size would be unset only if
+ there were some problem obtaining the value from the oper-
+ ating system (and setupterm would still fail). For that
+ reason, the LINES and COLUMNS environment variables may be
+ useful for working around window-size problems. Those
+ have the drawback that if the window is resized, those
+ variables must be recomputed and reassigned. To do this
+ more easily, use the resize(1) program.
+
+
+
The tset command uses these environment variables:
SHELL
@@ -298,13 +369,12 @@
TERMCAP
may denote the location of a termcap database. If it
- is not an absolute pathname, e.g., begins with a `/',
+ is not an absolute pathname, e.g., begins with a "/",
tset removes the variable from the environment before
looking for the terminal description.
-