This program initializes terminals.
First, tset retrieves the current terminal mode settings for your
@@ -79,48 +81,51 @@
1. The terminal argument specified on the command line.
- 2. The value of the TERM environmental variable.
+ 2. The value of the TERM environment variable.
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 convention, getty does this job by setting TERM
+ error output device in the /etc/ttys file. (On System V hosts and
+ systems using that convention, getty(8) 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", is not suitable for curses
+ applications.
- 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
- 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 terminal description for the terminal is retrieved. If
- no terminal description is found for the type, the user is prompted for
- another terminal type.
+ If the terminal type was not specified on the command-line, the -m
+ option mappings are then applied; see subsection "Terminal Type
+ Mapping". 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
+ terminal description for the terminal is retrieved. If no terminal
+ description is found for the type, the user is prompted for another
+ terminal type.
Once the terminal description is retrieved,
- o if the "-w" option is enabled, tset may update the terminal's
+ o if the "-w" option is enabled, tset may update the terminal's
window size.
- If the window size cannot be obtained from the operating system,
- but the terminal description (or environment, e.g., LINES and
- COLUMNS variables specify this), use this to set the operating
+ If the window size cannot be obtained from the operating system,
+ but the terminal description (or environment, e.g., LINES and
+ COLUMNS variables specify this), use this to set the operating
system's notion of the window size.
- o if the "-c" option is enabled, the backspace, interrupt and line
+ o if the "-c" option is enabled, the backspace, interrupt and line
kill characters (among many other things) are set
- o unless the "-I" option is enabled, the terminal and tab
- initialization strings are sent to the standard error output, and
- tset waits one second (in case a hardware reset was issued).
+ o unless the "-I" option is enabled, the terminal and tab
+ initialization strings are sent to the standard error output, and,
+ if the terminal device does not appear to be a pseudoterminal (as
+ might be used by a terminal emulator program), tset waits one
+ second in case a hardware reset was issued.
- o Finally, if the erase, interrupt and line kill characters have
- changed, or are not set to their default values, their values are
+ o 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 the terminal modes to "sane" values:
o sets cooked and echo modes,
@@ -132,10 +137,10 @@
o resets any unset special characters to their default values
before doing the terminal initialization described above. Also, rather
- than using the terminal initialization strings, it uses the terminal
+ than using the terminal initialization strings, it uses the terminal
reset strings.
- The reset command is useful after a program dies leaving a terminal in
+ The reset command is useful after a program dies leaving a terminal in
an abnormal state:
o you may have to type
@@ -143,76 +148,31 @@
<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
+ to work, as carriage-return may no longer work in the abnormal
state.
o 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.
-
- -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 the section
- TERMINALTYPEMAPPING for more information.
-
- -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 system's default values.
-
- -q The terminal type is displayed to the standard output, 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 SETTINGTHE
- ENVIRONMENT 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 setupterm(3x).
- 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" notation, 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.
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 are for sh. Note, the csh commands set and unset
+ the SHELL environment variable ends in "csh", the commands are for
+ csh(1), otherwise, they are for sh(1). 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 environment correctly:
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 variable is often something
+ /etc/ttys file or the TERM environment variable is often something
generic like network, dialup, or unknown. When tset is used in a
startup script it is often desirable to provide information about the
type of terminal used on such ports.
@@ -254,148 +214,188 @@
No whitespace characters are permitted in the -m option 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
+ that csh users insert a backslash character ("\") before any
exclamation marks ("!").
-
- A reset command appeared in 2BSD (April 1979), written by Kurt Shoens.
- This program set the erase and kill characters to ^H (backspace) and @
- respectively. Mark Horton improved that in 3BSD (October 1979), adding
- intr, quit, start/stop and eof characters as well as changing the
- program to avoid modifying any user settings.
+
+ The options are as follows:
- Later in 4.1BSD (December 1980), Mark Horton added a call to the tset
- program using the -I and -Q options, i.e., using that to improve the
- terminal modes. With those options, that version of reset did not use
- the termcap database.
+ -c Set control characters and modes.
- A separate tset command was provided in 2BSD by Eric Allman. While the
- oldest published source (from 1979) provides both tset and reset,
- Allman's comments in the 2BSD source code indicate that he began work
- in October 1977, continuing development over the next few years.
+ -ech
+ Set the erase character to ch.
- In September 1980, Eric Allman modified tset, adding the code from the
- existing "reset" feature when tset was invoked as reset. Rather than
- simply copying the existing program, in this merged version, tset used
- the termcap database to do additional (re)initialization of the
- terminal. This version appeared in 4.1cBSD, late in 1982.
+ -I Do not send the terminal or tab initialization strings to the
+ terminal.
+
+ -ich
+ Set the interrupt character to ch.
+
+ -kch
+ Set the line kill character to ch.
+
+ -mmapping
+ Specify a mapping from a port type to a terminal; see subsection
+ "Terminal Type Mapping".
+
+ -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 system's default values.
- Other developers (e.g., Keith Bostic and Jim Bloom) continued to modify
- tset until 4.4BSD was released in 1993.
+ -q The terminal type is displayed to the standard output, and the
+ terminal is not initialized in any way. The option "-" by itself
+ is equivalent but archaic.
- The ncurses implementation was lightly adapted from the 4.4BSD sources
- for a terminfo environment by Eric S. Raymond <esr@snark.thyrsus.com>.
+ -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 subsection "Setting the
+ Environment".
-
- Neither IEEE Std 1003.1/The Open Group Base Specifications Issue 7
+ -V reports the version of ncurses which was used in this program, and
+ exits.
+
+ -w Resize the window to match the size deduced via setupterm(3x).
+ 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" notation, i.e., control-h may
+ be specified as "^H" or "^h".
+
+ If neither -c or -w is given, both options are assumed.
+
+
+
+ The tset command uses these environment variables:
+
+ SHELL
+ tells tset whether to initialize TERM using sh(1) or csh(1)
+ syntax.
+
+ TERM Denotes your terminal type. Each terminal type is distinct,
+ though many are similar.
+
+ TERMCAP
+ may denote the location of a termcap database. If it is not an
+ absolute pathname, e.g., begins with a "/", tset removes the
+ variable from the environment before looking for the terminal
+ description.
+
+
+
+ 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 obsolete. However, each of those systems still provides
- tset. In fact, the commonly-used reset utility is always an alias for
+ The AT&T tput utility (AIX, HP-UX, 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 obsolete. 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.
+ The tset utility provides backward compatibility with BSD environments;
+ under most modern Unices, /etc/inittab and getty(8) can set TERM
+ appropriately for each dial-up line, obviating what was tset's most
+ important use. This implementation behaves like 4.4BSD tset, with a
+ few exceptions we shall consider now.
- A few options are different because the TERMCAP variable is no longer
- supported under terminfo-based ncurses:
+ 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
+ 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.
+ 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 beginning with an upper-case
+ There was an undocumented 4.4BSD feature that invoking tset via a link
+ named "TSET" (or via any other name beginning with an upper-case
letter) set the terminal to use upper-case only. This feature has been
omitted.
The -A, -E, -h, -u and -v options were deleted from the tset utility in
- 4.4BSD. 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
+ 4.4BSD. 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 -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
+ 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
+ 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.
- As of 4.4BSD, executing tset as reset no longer implies the -Q option.
+ 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.
- The -c and -w options are not found in earlier implementations.
+ The -c and -w options are not found in earlier implementations.
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
+ 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
+ o In ncurses, tset obtains the window size using setupterm(3x), which
+ may be from the operating system, the LINES and COLUMNS environment
variables or the terminal description.
- Obtaining the window size from the terminal description is common to
- both implementations, but considered obsolescent. 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
- operating 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.
+ Obtaining the window size from a terminal's type description is common
+ to both implementations, but considered obsolescent. Its only
+ practical use is for hardware terminals. Generally, the window size
+ will remain uninitialized only if there were a problem obtaining the
+ value from the operating system (and setupterm would still fail). The
+ LINES and COLUMNS environment variables may thus be useful for working
+ around window-size problems, but have the drawback that if the window
+ is resized, their values must be recomputed and reassigned. The
+ resize(1) program distributed with xterm(1) assists this activity.
-
- The tset command uses these environment variables:
-
- SHELL
- tells tset whether to initialize TERM using sh or csh syntax.
-
- TERM Denotes your terminal type. Each terminal type is distinct,
- though many are similar.
-
- TERMCAP
- may denote the location of a termcap database. If it is not an
- absolute pathname, e.g., begins with a "/", tset removes the
- variable from the environment before looking for the terminal
- description.
-
-
-
+ A reset command written by Kurt Shoens appeared in 1BSD (March 1978).
+ It set the erase and kill characters to ^H (backspace) and @
+ respectively. Mark Horton improved this reset in 3BSD (October 1979),
+ adding intr, quit, start/stop, and eof characters as well as changing
+ the program to avoid modifying any user settings. That version of
+ reset did not use termcap.
+
+ Eric Allman wrote a distinct tset command for 1BSD, using a forerunner
+ of termcap called ttycap. Allman's comments in the source code
+ indicate that he began work in October 1977, continuing development
+ over the next few years. By late 1979, it had migrated to termcap and
+ handled the TERMCAP variable. Later comments indicate that tset was
+ modified in September 1980 to use logic copied from the 3BSD "reset"
+ program when it was invoked as reset. This version appeared in
+ 4.1cBSD, late in 1982. Other developers such as Keith Bostic and Jim
+ Bloom continued to modify tset until 4.4BSD was released in 1993.
+
+ The ncurses implementation was lightly adapted from the 4.4BSD sources
+ to use the terminfo API by Eric S. Raymond <esr@snark.thyrsus.com>.