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NAME
tput - change terminal characteristics
SYNOPSIS
tput [-T type] operand...
DESCRIPTION
The tput utility shall display terminal-dependent information. The manner in which this
information is retrieved is unspecified. The information displayed shall clear the
terminal screen, initialize the user's terminal, or reset the user's terminal, depending
on the operand given. The exact consequences of displaying this information are
unspecified.
OPTIONS
The tput utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001,
Section 12.2, Utility Syntax Guidelines.
The following option shall be supported:
-T type
Indicate the type of terminal. If this option is not supplied and the TERM variable
is unset or null, an unspecified default terminal type shall be used. The setting
of type shall take precedence over the value in TERM .
OPERANDS
The following strings shall be supported as operands by the implementation in the POSIX
locale:
clear Display the clear-screen sequence.
init Display the sequence that initializes the user's terminal in an implementation-
defined manner.
reset Display the sequence that resets the user's terminal in an implementation-defined
manner.
If a terminal does not support any of the operations described by these operands, this
shall not be considered an error condition.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of tput:
LANG Provide a default value for the internationalization variables that are unset or
null. (See the Base Definitions volume of IEEE Std 1003.1-2001, Section 8.2,
Internationalization Variables for the precedence of internationalization variables
used to determine the values of locale categories.)
LC_ALL If set to a non-empty string value, override the values of all the other
internationalization variables.
LC_CTYPE
Determine the locale for the interpretation of sequences of bytes of text data as
characters (for example, single-byte as opposed to multi-byte characters in
arguments).
LC_MESSAGES
Determine the locale that should be used to affect the format and contents of
diagnostic messages written to standard error.
NLSPATH
Determine the location of message catalogs for the processing of LC_MESSAGES .
TERM Determine the terminal type. If this variable is unset or null, and if the -T
option is not specified, an unspecified default terminal type shall be used.
ASYNCHRONOUS EVENTS
Default.
STDOUT
If standard output is a terminal device, it may be used for writing the appropriate
sequence to clear the screen or reset or initialize the terminal. If standard output is
not a terminal device, undefined results occur.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 The requested string was written successfully.
1 Unspecified.
2 Usage error.
3 No information is available about the specified terminal type.
4 The specified operand is invalid.
>4 An error occurred.
CONSEQUENCES OF ERRORS
If one of the operands is not available for the terminal, tput continues processing the
remaining operands.
The following sections are informative.
APPLICATION USAGE
The difference between resetting and initializing a terminal is left unspecified, as they
vary greatly based on hardware types. In general, resetting is a more severe action.
Some terminals use control characters to perform the stated functions, and on such
terminals it might make sense to use tput to store the initialization strings in a file or
environment variable for later use. However, because other terminals might rely on system
calls to do this work, the standard output cannot be used in a portable manner, such as
the following non-portable constructs:
ClearVar=`tput clear`
tput reset | mailx -s "Wake Up" ddg
EXAMPLES
1. Initialize the terminal according to the type of terminal in the environmental
variable TERM . This command can be included in a .profile file.
tput init
2. Reset a 450 terminal.
tput -T 450 reset
RATIONALE
The list of operands was reduced to a minimum for the following reasons:
* The only features chosen were those that were likely to be used by human users
interacting with a terminal.
* Specifying the full terminfo set was not considered desirable, but the standard
developers did not want to select among operands.
* This volume of IEEE Std 1003.1-2001 does not attempt to provide applications with
sophisticated terminal handling capabilities, as that falls outside of its assigned
scope and intersects with the responsibilities of other standards bodies.
The difference between resetting and initializing a terminal is left unspecified as this
varies greatly based on hardware types. In general, resetting is a more severe action.
The exit status of 1 is historically reserved for finding out if a Boolean operand is not
set. Although the operands were reduced to a minimum, the exit status of 1 should still be
reserved for the Boolean operands, for those sites that wish to support them.
FUTURE DIRECTIONS
None.
SEE ALSO
stty , tabs
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee document. The
original Standard can be obtained online at http://www.opengroup.org/unix/online.html .