xenial (1) tput.1posix.gz

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PROLOG
       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.


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  POSIX.1‐2008,  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 POSIX.1‐2008, 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  POSIX.1‐2008  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

       The Base Definitions volume of POSIX.1‐2008, Chapter 8,  Environment  Variables,  Section  12.2,  Utility
       Syntax Guidelines


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications  Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
       and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

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