termdef

Purpose

     Queries terminal characteristics.

Library

     Standard C Library (libc.a)

Syntax

     char *termdef (fildes, c)
     int fildes;
     char c;

Description

     The  termdef  subroutine returns  a  pointer  to a  null-
     terminated  static  character  string that  identifies  a
     characteristic of the  terminal that is open  on the file
     descriptor  specified by  the  fildes  parameter.  The  c
     parameter  specifies the  characteristic  that  is to  be
     queried.   termdef determines  this  information by  per-
     forming the following actions:

     1.  It queries  the terminal device, using  the Query HFT
         Device command, which is discussed on page 4-60.

     2.  If the query fails, then termdef uses the value of an
         environment variable.

     3.  If the environment variable  is not set, then termdef
         returns the default value  specified in the following
         table.

     The following list shows the  valid request types and the
     corresponding environment variables that  are used if the
     Query HFT Device command fails:

                       Environment  Default
                    c  Variable     Value      Description

                    t  TERM         ""ibm5151""The terminal type
                    l  LINES        NULL       The number  of lines  or rows,
                                               based on the current font
                    c  COLUMNS      NULL       The   number    of   character
                                               columns, based  on the current
                                               font.

     Note:  When  fildes identifies an  asynchronous terminal,
     the Query HFT  Device command always fails  and the envi-
     ronment variable is always checked.  The TERM variable is

     automatically  set  each  time  you log  in.   LINES  and
     COLUMNS need to be set only if:

     o   You are  using an  asynchronous terminal and  want to
         override the lines and  cols settings in the terminfo
         data base, or
     o   Your asynchronous  terminal has an unusual  number of
         lines or  columns and you are  running an application
         that uses termdef, but not terminfo.

     This is true because  the terminfo initialization subrou-
     tine, setupterm, calls termdef to determine the number of
     lines  and columns  on  the display.   If termdef  cannot
     supply this  information, then setupterm uses  the values
     in the terminfo data base.

Related Information

     In this book:  "Terminfo Level Subroutines,"  "terminfo,"
     and "Query HFT Device Command."

     The display and termdef  commands in AIX Operating System
     Commands Reference.