tput(1) User commands tput(1)
NAME
tput - initialize a terminal, exercise its capabilities, or query
terminfo database
SYNOPSIS
tput [-T terminal-type] {cap-code [parameter ...]} ...
tput [-T terminal-type] [-x] clear
tput [-T terminal-type] init
tput [-T terminal-type] reset
tput [-T terminal-type] longname
tput -S
tput -V
DESCRIPTION
tput uses the terminfo library and database to make terminal-specific
capabilities and information available to the shell, to initialize or
reset the terminal, or to report a description of the current (or
specified) terminal type. Terminal capabilities are accessed by
cap-code.
terminfo(5) discusses terminal capabilities at length and presents a
complete list of cap-codes.
When retrieving capability values, the result depends upon the
capability's type.
Boolean tput sets its exit status to 0 if the terminal possesses
cap-code, and 1 if it does not.
numeric tput writes cap-code's decimal value to the standard output
stream if defined (-1 if it is not) followed by a newline.
string tput writes cap-code's value to the standard output stream if
defined, without a trailing newline.
Before using a value returned on the standard output, the application
should test tput's exit status to be sure it is 0; see section "EXIT
STATUS" below.
Operands
Generally, an operand is a cap-code, a capability code from the
terminal database, or a parameter thereto. Three others are specially
recognized by tput: init, reset, and longname. Although these resemble
capability codes, they in fact receive special handling; we term them
"pseudo-capabilities".
cap-code indicates a capability from the terminal database.
If cap-code is of string type and takes parameters, tput
interprets arguments following cap-code as the parameters,
up to the (fixed) quantity the capability requires.
Most parameters are numeric. 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 initializes the terminal. If the terminal database is
present and an entry for the user's terminal type exists,
the following occur.
(1) tput retrieves the terminal's mode settings. It
successively tests the file descriptors corresponding
to
o the standard error stream,
o the standard output stream,
o the standard input stream, and
o /dev/tty
to obtain terminal settings. Having retrieved them,
tput remembers which descriptor to use for further
updates.
(2) If the terminal dimensions cannot be obtained from the
operating system, but the environment or terminal type
database entry describes them, tput updates the
operating system's notion of them.
(3) tput updates the terminal modes.
o Any delays specified in the entry (for example,
when a newline is sent) are set in the terminal
driver.
o Tab expansion is turned on or off per the
specification in the entry, and
o if tabs are not expanded, standard tabs (every 8
spaces) are set.
(4) If initialization capabilities, detailed in subsection
"Tabs and Initialization" of terminfo(5), are present,
tput writes them to the standard output stream.
(5) tput flushes the standard output stream.
If an entry lacks the information needed for an activity
above, that activity is silently skipped.
reset re-initializes the terminal. A reset differs from
initialization in two ways.
(1) tput sets the the terminal modes to a "sane" state,
o enabling cooked and echo modes,
o disabling cbreak and raw modes,
o enabling newline translation, and
o setting any unset special characters to their
default values.
(2) If any reset capabilities are defined for the terminal
type, tput writes them to the output stream.
Otherwise, tput uses any defined initialization
capabilities. Reset capabilities are detailed in
subsection "Tabs and Initialization" of terminfo(5).
longname A terminfo entry begins with one or more names by which an
application can refer to the entry, before the list of
terminal capabilities. The names are separated by "|"
characters. X/Open Curses terms the last name the "long
name", and indicates that it may include blanks.
tic warns if the last name does not include blanks, to
accommodate old terminfo entries that treated the long name
as an optional feature. The long name is often referred to
as the description field.
If the terminal database is present and an entry for the
user's terminal type exists, tput reports its description to
the standard output stream, without a trailing newline. See
terminfo(5).
Note: Redirecting the output of "tput init" or "tput reset" to a file
will capture only part of their actions. Changes to the terminal modes
are not affected by file descriptor redirection, since the terminal
modes are altered via ioctl(2).
Aliases
If tput is invoked via link with any of the names clear, init, or
reset, it operates as if run with the corresponding (pseudo-)capability
operand. For example, executing a link named reset that points to tput
has the same effect as "tput reset".
This feature was introduced by ncurses 5.2 in 2000. It is rarely used:
clear is a separate program, which is both smaller and more frequently
executed.
init has the same name as another program in widespread use.
reset is provided by the tset(1) utility (also via a link named
reset).
Terminal Size
Besides the pseudo-capabilities (such as init), tput treats the lines
and cols cap-codes specially: it may call setupterm(3X) to obtain the
terminal size.
o First, tput attempts to obtain these capabilities from the terminal
database. This generally fails for terminal emulators, which lack
a fixed window size and thus omit the capabilities.
o It then asks the operating system for the terminal's size, which
generally works, unless the connection is via a serial line that
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,
ultimately, the terminal database).
OPTIONS
-S retrieves more than one capability per invocation of tput.
The capabilities must be passed to tput from the standard
input stream instead of from the command line (see section
"EXAMPLES" below). Only one cap-code is allowed per line.
The -S option changes the meanings of the 0 and 1 exit
statuses (see section "EXIT STATUS" below).
Some capabilities use string parameters rather than numeric
ones. tput employs a built-in table and the presence of
parameters in its input to decide how to interpret them, and
whether to use tparm(3X).
-T type indicates the terminal's type. Normally this option is
unnecessary, because a default is taken from the TERM
environment variable. If specified, the environment variables
LINES and COLUMNS are also ignored.
-V reports the version of ncurses associated with tput, and exits
with a successful status.
-x prevents "tput clear" from attempting to clear the scrollback
buffer.
EXIT STATUS
Normally, one should interpret tput's exit statuses as follows.
Status Meaning When -S Not Specified
------------------------------------------------------------------------
0 Boolean or string capability present
1 Boolean or numeric capability absent
2 usage error or no terminal type specified
3 unrecognized terminal type
4 unrecognized capability code
>4 system error (4 + errno)
When the -S option is used, some statuses change meanings.
Status Meaning When -S Specified
------------------------------------------------------------------------
0 all operands interpreted
1 unused
4 some operands not interpreted
ENVIRONMENT
tput reads one environment variable.
TERM denotes the terminal type. Each terminal type is distinct,
though many are similar. The -T option overrides its value.
FILES
/opt/local/share/tabset
tab stop initialization database
/opt/local/share/terminfo
compiled terminal description database
PORTABILITY
Over time ncurses tput has differed from that of System V in two
important respects, one now mostly historical.
o "tput cap-code" writes to the standard output, which need not be a
terminal device. However, the operands that manipulate terminal
modes might not use the standard output.
System V tput's init and reset operands use logic from 4.1cBSD
tset, manipulating terminal modes. It checks the same file
descriptors (and /dev/tty) for association with a terminal device
as ncurses now does, and if none are, finally assumes a 1200 baud
terminal. When updating terminal modes, it ignores errors.
Until ncurses 6.1 (see section "HISTORY" below), tput did not
modify terminal modes. It now employs a scheme similar to
System V, using functions shared with tset (and ultimately based on
4.4BSD tset). If it is not able to open a terminal (for instance,
when run by cron(1)), tput exits with an error status.
o System V tput assumes that the type of a cap-code operand is
numeric if all the characters of its value are decimal numbers; if
they are not, it treats cap-code as a string capability.
Most implementations that provide support for cap-code operands use
the tparm(3X) function to expand its parameters. That function
expects a mixture of numeric and string parameters, requiring tput
to know which type to use.
ncurses tput uses a table to determine the parameter types for the
standard cap-code operands, and an internal function to analyze
nonstandard cap-code operands.
While more reliable than System V'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, and modified it to interpret
multiple cap-codes (and parameters) on the command line. Portable
applications should not rely upon this feature; ncurses offers it
to support applications written specifically for OpenBSD.
This implementation, unlike others, accepts both termcap and terminfo
cap-codes if termcap support is compiled in. In that case, however,
the predefined termcap and terminfo codes have two ambiguities; ncurses
assumes the terminfo code.
o The cap-code dl means delete_line to termcap but parm_delete_line
to terminfo. termcap uses the code DL for parm_delete_line.
terminfo uses the code dl1 for delete_line.
o The cap-code ed means exit_delete_mode to termcap but clr_eos to
terminfo. termcap uses the code cd for clr_eos. terminfo uses the
code rmdc for exit_delete_mode.
The longname operand, -S option, and the parameter-substitution
features used in the cup example below, were not supported in AT&T/USL
curses before SVr4 (1989). Later, 4.3BSD-Reno (1990) added support for
longname, and in 1994, NetBSD added support for the parameter-
substitution features.
IEEE Std 1003.1/The Open Group Base Specifications Issue 7
(POSIX.1-2008) documents only the clear, init, and reset operands. A
few observations of interest arise from that selection.
o ncurses supports clear as it does any other standard cap-code. The
others (init and longname) do not correspond to terminal
capabilities.
o The tput on SVr4-based systems such as Solaris, IRIX64, and HP-UX,
as well as others such as AIX and Tru64, also support standard
cap-code operands.
o A few platforms such as FreeBSD recognize termcap codes rather than
terminfo capability codes in their respective tput commands. Since
2010, NetBSD's tput uses terminfo codes. Before that, it (like
FreeBSD) recognized termcap codes.
Beginning in 2021, FreeBSD uses ncurses tput, configured for both
terminfo (tested first) and termcap (as a fallback).
Because (apparently) all certified Unix systems support the full set of
capability codes, the reason for documenting only a few may not be
apparent.
o X/Open Curses Issue 7 documents tput differently, with cap-code 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 capability database.
o While it is certainly possible to write a tput program without
using curses, no system with a curses implementation provides a
tput utility that does not also support standard cap-codes.
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 (that is, System V curses behavior).
o It assigns exit status 4 to "invalid operand", which may have the
same meaning as "unknown capability". For instance, the source
code for Solaris xcurses uses the term "invalid" in this case.
o It assigns exit status 255 to a numeric variable that is not
specified in the terminfo database. That likely is a documentation
error, mistaking the "-1" written to the standard output to
indicate an absent or cancelled numeric capability for an
(unsigned) exit status.
The various System V implementations (AIX, HP-UX, Solaris) use the same
exit statuses as ncurses.
NetBSD curses documents exit statuses that correspond to neither
ncurses nor X/Open Curses.
HISTORY
Bill Joy wrote a tput command during development of 4BSD in October
1980. This initial version only cleared the screen, and did not ship
with official distributions.
System V developed a different tput command.
o SVr2 (1984) provided a rudimentary tput that checked the parameter
against each predefined capability and returned the corresponding
value. This version of tput did not use tparm(3X) for
parameterized capabilities.
o SVr3 (1987) replaced that with a more extensive program whose
support for init and reset operands (more than half the program)
incorporated the reset feature of BSD tset written by Eric Allman.
o SVr4 (1989) added color initialization by using the orig_colors
(oc) and orig_pair (op) capabilities in its init logic.
Keith Bostic refactored BSD tput for shipment in 4.3BSD-Tahoe (1988),
then replaced it the next year with a new implementation based on
System V tput. Bostic's version similarly accepted some parameters
named for terminfo (pseudo-)capabilities: clear, init, longname, and
reset. However, because he had only termcap available, it accepted
termcap codes for other capabilities. Also, Bostic's BSD tput did not
modify the terminal modes as the earlier BSD tset had done.
At the same time, Bostic added a shell script named "clear" that used
tput to clear the screen. Both of these appeared in 4.4BSD, becoming
the "modern" BSD implementation of tput.
The origin of ncurses tput lies outside both System V and BSD, in 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. Incorporating
the portions dealing with terminal capabilities almost without change,
Raymond made improvements to the way command-line parameters were
handled.
Before ncurses 6.1 (2018), its tset and tput utilities differed.
o tset was more effective, resetting the terminal modes and special
characters.
o On the other hand, tset's repertoire of terminal capabilities for
resetting the terminal was more limited; it had only equivalents of
reset_1string (rs1), reset_2string (rs2), and reset_file (rf), and
not the tab stop and margin update features of tput.
The reset program is traditionally an alias for tset due to its ability
to reset terminal modes and special characters.
As of ncurses 6.1, the "reset" features of the two programs are
(mostly) the same. Two minor differences remain.
o The tset program waits one second when resetting, in case the
terminal happens to be a hardware device.
o The two programs write the terminal initialization strings to
different streams; that is, standard error for tset and standard
output for tput.
EXAMPLES
tput init
Initialize the terminal according to the type of terminal in the
TERM environment variable. If the system does not reliably
initialize the terminal upon login, this command can be included
in $HOME/.profile after exporting the TERM environment variable.
tput -T5620 reset
Reset an AT&T 5620 terminal, overriding the terminal type in the
TERM environment variable.
tput cnorm
Set cursor to normal visibility.
tput home
Move the cursor to row 0, column 0: the upper left corner of the
screen, usually known as the "home" cursor position.
tput clear
Clear the screen: write the clear_screen capability's value to
the standard output stream.
tput cols
Report the number of columns used by the current terminal type.
tput -Tadm3a cols
Report the number of columns used by an ADM-3A terminal.
strong=`tput smso` normal=`tput rmso`
Set shell variables to capability values: strong and normal, to
begin and end, respectively, stand-out mode for the terminal.
One might use these to present a prompt.
printf "${strong}Username:${normal} "
tput hc
Indicate via exit status whether the terminal is a hard copy
device.
tput cup 23 4
Move the cursor to row 23, column 4.
tput cup
Report the value of the cursor_address (cup) capability (used
for cursor movement), with no parameters substituted.
tput longname
Report the terminfo database's description of the terminal type
specified in the TERM environment variable.
tput -S
Process multiple capabilities. The -S option can be profitably
used with a shell "here document".
$ tput -S <<!
> clear
> cup 10 10
> bold
> !
The foregoing clears the screen, moves the cursor to position
(10, 10) and turns on bold (extra bright) mode.
tput clear cup 10 10 bold
Perform the same actions as the foregoing "tput -S" example.
SEE ALSO
clear(1), stty(1), tabs(1), tset(1), curs_termcap(3X), terminfo(5)
ncurses 6.5 2024-04-20 tput(1)
ncurses 6.5 - Generated Tue Apr 30 19:05:36 CDT 2024