https://invisible-island.net/ncurses/man/
tput(1) General Commands Manual tput(1)
tput, reset - initialize a terminal or query terminfo database
tput [-Ttype] capname [parameters]
tput [-Ttype] [-x] clear
tput [-Ttype] init
tput [-Ttype] reset
tput [-Ttype] longname
tput -S <<
tput -V
The tput utility uses the terminfo database to make the values of
terminal-dependent capabilities and information available to the shell
(see sh(1)), to initialize or reset the terminal, or return the long
name of the requested terminal type. The result depends upon the
capability's type:
string
tput writes the string to the standard output. No trailing
newline is supplied.
integer
tput writes the decimal value to the standard output, with a
trailing newline.
boolean
tput simply sets the exit code (0 for TRUE if the terminal has
the capability, 1 for FALSE if it does not), and writes nothing
to the standard output.
Before using a value returned on the standard output, the application
should test the exit code (e.g., $?, see sh(1)) to be sure it is 0.
(See the EXIT CODES and DIAGNOSTICS sections.) For a complete list of
capabilities and the capname associated with each, see terminfo(5).
-S allows more than one capability per invocation of tput. The
capabilities must be passed to tput from the standard input
instead of from the command line (see example). Only one
capname is allowed per line. The -S option changes the meaning
of the 0 and 1 boolean and string exit codes (see the EXIT CODES
section).
Because some capabilities may use string parameters rather than
numbers, tput uses a table and the presence of parameters in its
input to decide whether to use tparm(3x), and how to interpret
the parameters.
-Ttype indicates the type of terminal. Normally this option is
unnecessary, because the default is taken from the environment
variable TERM. If -T is specified, then the shell variables
LINES and COLUMNS will also be ignored.
-V reports the version of ncurses which was used in this program,
and exits.
-x do not attempt to clear the terminal's scrollback buffer using
the extended "E3" capability.
A few commands (init, reset and longname) are special; they are defined
by the tput program. The others are the names of capabilities from the
terminal database (see terminfo(5) for a list). Although init and
reset resemble capability names, tput uses several capabilities to
perform these special functions.
capname
indicates the capability from the terminal database.
If the capability is a string that takes parameters, the
arguments following the capability will be used as parameters
for the string.
Most parameters are numbers. Only a few terminal capabilities
require string parameters; tput uses a table to decide which to
pass as strings. Normally tput uses tparm(3x) to perform the
substitution. If no parameters are given for the capability,
tput writes the string without performing the substitution.
init If the terminal database is present and an entry for the user's
terminal exists (see -Ttype, above), the following will occur:
(1) first, tput 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
settings, tput remembers which file descriptor to use when
updating settings.
(2) 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), update the
operating system's notion of the window size.
(3) the terminal modes will be updated:
o any delays (e.g., newline) specified in the entry will
be set in the tty driver,
o tabs expansion will be turned on or off according to
the specification in the entry, and
o if tabs are not expanded, standard tabs will be set
(every 8 spaces).
(4) if present, the terminal's initialization strings will be
output as detailed in the terminfo(5) section on Tabs and
Initialization,
(5) output is flushed.
If an entry does not contain the information needed for any of
these activities, that activity will silently be skipped.
reset This is similar to init, with two differences:
(1) before any other initialization, the terminal modes will be
reset to a "sane" state:
o set cooked and echo modes,
o turn off cbreak and raw modes,
o turn on newline translation and
o reset any unset special characters to their default
values
(2) Instead of putting out initialization strings, the
terminal's reset strings will be output if present (rs1,
rs2, rs3, rf). If the reset strings are not present, but
initialization strings are, the initialization strings will
be output.
Otherwise, reset acts identically to init.
longname
If the terminal database is present and an entry for the user's
terminal exists (see -Ttype above), then the long name of the
terminal will be put out. The long name is the last name in the
first line of the terminal's description in the terminfo
database [see term(5)].
tput handles the clear, init and reset commands specially: it allows
for the possibility that it is invoked by a link with those names.
If tput is invoked by a link named reset, this has the same effect as
tput reset. The tset(1) utility also treats a link named reset
specially.
Before ncurses 6.1, the two utilities were different from each other:
o tset utility reset the terminal modes and special characters (not
done with tput).
o On the other hand, tset's repertoire of terminal capabilities for
resetting the terminal was more limited, i.e., only reset_1string,
reset_2string and reset_file in contrast to the tab-stops and
margins which are set by this utility.
o The reset program is usually an alias for tset, because of this
difference with resetting terminal modes and special characters.
With the changes made for ncurses 6.1, the reset feature of the two
programs is (mostly) the same. A few differences remain:
o The tset program waits one second when resetting, in case it
happens to be a hardware terminal.
o The two programs write the terminal initialization strings to
different streams (i.e., the standard error for tset and the
standard output for tput).
Note: although these programs write to different streams,
redirecting their output to a file will capture only part of their
actions. The changes to the terminal modes are not affected by
redirecting the output.
If tput is invoked by a link named init, this has the same effect as
tput init. Again, you are less likely to use that link because another
program named init has a more well-established use.
Besides the special commands (e.g., clear), tput treats certain
terminfo capabilities specially: lines and cols. tput calls
setupterm(3x) to obtain the terminal size:
o first, it gets the size from the terminal database (which generally
is not provided for terminal emulators which do not have a fixed
window size)
o then it asks the operating system for the terminal's size (which
generally works, unless connecting via a serial line which does not
support NAWS: negotiations about window size).
o finally, it inspects the environment variables LINES and COLUMNS
which may override the terminal size.
If the -T option is given tput ignores the environment variables by
calling use_tioctl(TRUE), relying upon the operating system (or
finally, the terminal database).
tput init
Initialize the terminal according to the type of terminal in the
environmental variable TERM. This command should be included in
everyone's .profile after the environmental variable TERM has been
exported, as illustrated on the profile(5) manual page.
tput -T5620 reset
Reset an AT&T 5620 terminal, overriding the type of terminal in
the environmental variable TERM.
tput cup 0 0
Send the sequence to move the cursor to row 0, column 0 (the upper
left corner of the screen, usually known as the "home" cursor
position).
tput clear
Echo the clear-screen sequence for the current terminal.
tput cols
Print the number of columns for the current terminal.
tput -T450 cols
Print the number of columns for the 450 terminal.
bold=`tput smso` offbold=`tput rmso`
Set the shell variables bold, to begin stand-out mode sequence,
and offbold, to end standout mode sequence, for the current
terminal. This might be followed by a prompt: echo "${bold}Please
type in your name: ${offbold}\c"
tput hc
Set exit code to indicate if the current terminal is a hard copy
terminal.
tput cup 23 4
Send the sequence to move the cursor to row 23, column 4.
tput cup
Send the terminfo string for cursor-movement, with no parameters
substituted.
tput longname
Print the long name from the terminfo database for the type of
terminal specified in the environmental variable TERM.
tput -S <<!
> clear
> cup 10 10
> bold
> !
This example shows tput processing several capabilities in one
invocation. It clears the screen, moves the cursor to position
10, 10 and turns on bold (extra bright) mode. The list is
terminated by an exclamation mark (!) on a line by itself.
/usr/share/terminfo
compiled terminal description database
/usr/share/tabset/*
tab settings for some terminals, in a format appropriate to be
output to the terminal (escape sequences that set margins and
tabs); for more information, see the Tabs and Initialization,
section of terminfo(5)
If the -S option is used, tput checks for errors from each line, and if
any errors are found, will set the exit code to 4 plus the number of
lines with errors. If no errors are found, the exit code is 0. No
indication of which line failed can be given so exit code 1 will never
appear. Exit codes 2, 3, and 4 retain their usual interpretation. If
the -S option is not used, the exit code depends on the type of
capname:
boolean
a value of 0 is set for TRUE and 1 for FALSE.
string a value of 0 is set if the capname is defined for this
terminal type (the value of capname is returned on standard
output); a value of 1 is set if capname is not defined for
this terminal type (nothing is written to standard output).
integer
a value of 0 is always set, whether or not capname is defined
for this terminal type. To determine if capname is defined
for this terminal type, the user must test the value written
to standard output. A value of -1 means that capname is not
defined for this terminal type.
other reset or init may fail to find their respective files. In
that case, the exit code is set to 4 + errno.
Any other exit code indicates an error; see the DIAGNOSTICS section.
tput prints the following error messages and sets the corresponding
exit codes.
exit code error message
---------------------------------------------------------------------
0 (capname is a numeric variable that is not specified in
the terminfo(5) database for this terminal type, e.g.
tput -T450 lines and tput -Thp2621 xmc)
1 no error message is printed, see the EXIT CODES section.
2 usage error
3 unknown terminal type or no terminfo database
4 unknown terminfo capability capname
>4 error occurred in -S
---------------------------------------------------------------------
The tput command was begun by Bill Joy in 1980. The initial version
only cleared the screen.
AT&T System V provided a different tput command:
o SVr2 provided a rudimentary tput which checked the parameter
against each predefined capability and returned the corresponding
value. This version of tput did not use tparm(3x) for the
capabilities which are parameterized.
o SVr3 replaced that, a year later, by a more extensive program whose
init and reset subcommands (more than half the program) were
incorporated from the reset feature of BSD tset written by Eric
Allman.
o SVr4 added color initialization using the orig_colors and orig_pair
capabilities in the init subcommand.
Keith Bostic replaced the BSD tput command in 1989 with a new
implementation based on the AT&T System V program tput. Like the AT&T
program, Bostic's version accepted some parameters named for terminfo
capabilities (clear, init, longname and reset). However (because he
had only termcap available), it accepted termcap names for other
capabilities. Also, Bostic's BSD tput did not modify the terminal I/O
modes as the earlier BSD tset had done.
At the same time, Bostic added a shell script named "clear", which used
tput to clear the screen.
Both of these appeared in 4.4BSD, becoming the "modern" BSD
implementation of tput.
This implementation of tput began from a different source than AT&T or
BSD: Ross Ridge's mytinfo package, published on comp.sources.unix in
December 1992. Ridge's program made more sophisticated use of the
terminal capabilities than the BSD program. Eric Raymond used that
tput program (and other parts of mytinfo) in ncurses in June 1995.
Using the portions dealing with terminal capabilities almost without
change, Raymond made improvements to the way the command-line
parameters were handled.
This implementation of tput differs from AT&T tput in two important
areas:
o tput capname writes to the standard output. That need not be a
regular terminal. However, the subcommands which manipulate
terminal modes may not use the standard output.
The AT&T implementation's init and reset commands use the BSD
(4.1c) tset source, which manipulates terminal modes. It
successively tries standard output, standard error, standard input
before falling back to "/dev/tty" and finally just assumes a 1200Bd
terminal. When updating terminal modes, it ignores errors.
Until changes made after ncurses 6.0, tput did not modify terminal
modes. tput now uses a similar scheme, using functions shared with
tset (and ultimately based on the 4.4BSD tset). If it is not able
to open a terminal, e.g., when running in cron(1), tput will return
an error.
o AT&T tput guesses the type of its capname operands by seeing if all
of the characters are numeric, or not.
Most implementations which provide support for capname operands use
the tparm function to expand parameters in it. That function
expects a mixture of numeric and string parameters, requiring tput
to know which type to use.
This implementation uses a table to determine the parameter types
for the standard capname operands, and an internal library function
to analyze nonstandard capname operands.
Besides providing more reliable operation than AT&T's utility, a
portability problem is introduced by this analysis: An OpenBSD
developer adapted the internal library function from ncurses to
port NetBSD's termcap-based tput to terminfo. That had been
modified to interpret multiple commands on a line. Portable
applications should not rely upon this feature; ncurses provides it
to support applications written specifically for OpenBSD.
This implementation (unlike others) can accept both termcap and
terminfo names for the capname feature, if termcap support is compiled
in. However, the predefined termcap and terminfo names have two
ambiguities in this case (and the terminfo name is assumed):
o The termcap name dl corresponds to the terminfo name dl1 (delete
one line).
The terminfo name dl corresponds to the termcap name DL (delete a
given number of lines).
o The termcap name ed corresponds to the terminfo name rmdc (end
delete mode).
The terminfo name ed corresponds to the termcap name cd (clear to
end of screen).
The longname and -S options, and the parameter-substitution features
used in the cup example, were not supported in BSD curses before
4.3reno (1989) or in AT&T/USL curses before SVr4 (1988).
IEEE Std 1003.1/The Open Group Base Specifications Issue 7
(POSIX.1-2008) documents only the operands for clear, init and reset.
There are a few interesting observations to make regarding that:
o In this implementation, clear is part of the capname support. The
others (init and longname) do not correspond to terminal
capabilities.
o Other implementations of tput on SVr4-based systems such as
Solaris, IRIX64 and HPUX as well as others such as AIX and Tru64
provide support for capname operands.
o A few platforms such as FreeBSD recognize termcap names rather than
terminfo capability names in their respective tput commands. Since
2010, NetBSD's tput uses terminfo names. Before that, it (like
FreeBSD) recognized termcap names.
Beginning in 2021, FreeBSD uses the ncurses tput, configured for
both terminfo (tested first) and termcap (as a fallback).
Because (apparently) all of the certified Unix systems support the full
set of capability names, the reasoning for documenting only a few may
not be apparent.
o X/Open Curses Issue 7 documents tput differently, with capname and
the other features used in this implementation.
o That is, there are two standards for tput: POSIX (a subset) and
X/Open Curses (the full implementation). POSIX documents a subset
to avoid the complication of including X/Open Curses and the
terminal capabilities database.
o While it is certainly possible to write a tput program without
using curses, none of the systems which have a curses
implementation provide a tput utility which does not provide the
capname feature.
X/Open Curses Issue 7 (2009) is the first version to document
utilities. However that part of X/Open Curses does not follow existing
practice (i.e., Unix features documented in SVID 3):
o It assigns exit code 4 to "invalid operand", which may be the same
as unknown capability. For instance, the source code for Solaris'
xcurses uses the term "invalid" in this case.
o It assigns exit code 255 to a numeric variable that is not
specified in the terminfo database. That likely is a documentation
error, confusing the -1 written to the standard output for an
absent or cancelled numeric value versus an (unsigned) exit code.
The various Unix systems (AIX, HPUX, Solaris) use the same exit-codes
as ncurses.
NetBSD curses documents different exit codes which do not correspond to
either ncurses or X/Open.
clear(1), stty(1), tabs(1), tset(1), curs_termcap(3x), terminfo(5).
This describes ncurses version 6.3 (patch 20221126).
tput(1)