-<H2>ENVIRONMENT</H2><PRE>
- The following environment symbols are useful for
- customizing the runtime behavior of the <STRONG>ncurses</STRONG> library.
- The most important ones have been already discussed in
- detail.
-
- BAUDRATE
- The debugging library checks this environment symbol
- when the application has redirected output to a file.
- The symbol's numeric value is used for the baudrate.
- If no value is found <STRONG>ncurses</STRONG> uses 9600. This allows
- testers to construct repeatable test-cases that take
- into account costs that depend on baudrate.
-
- CC When set, change occurrences of the command_character
- (i.e., the <STRONG>cmdch</STRONG> capability) of the loaded terminfo
- entries to the value of this symbol. Very few
- terminfo entries provide this feature.
-
- COLUMNS
- Specify the width of the screen in characters.
- Applications running in a windowing environment
- usually are able to obtain the width of the window in
- which they are executing. If neither the $COLUMNS
- value nor the terminal's screen size is available,
- <STRONG>ncurses</STRONG> uses the size which may be specified in the
- terminfo database (i.e., the <STRONG>cols</STRONG> capability).
-
- It is important that your application use a correct
- size for the screen. However, this is not always
- possible because your application may be running on a
- host which does not honor NAWS (Negotiations About
- Window Size), or because you are temporarily running
- as another user.
-
- Either COLUMNS or LINES symbols may be specified
- independently. This is mainly useful to circumvent
- legacy misfeatures of terminal descriptions, e.g.,
- xterm which commonly specifies a 65 line screen. For
- best results, <STRONG>lines</STRONG> and <STRONG>cols</STRONG> should not be specified
- in a terminal description for terminals which are run
- as emulations.
-
- Use the <STRONG>use_env</STRONG> function to disable this feature.
-
- ESCDELAY
- Specifies the total time, in milliseconds, for which
- ncurses will await a character sequence, e.g., a
- function key. The default value, 1000 milliseconds,
- is enough for most uses. However, it is made a
- variable to accommodate unusual applications.
-
- The most common instance where you may wish to change
- this value is to work with slow hosts, e.g., running
- on a network. If the host cannot read characters
- rapidly enough, it will have the same effect as if
- the terminal did not send characters rapidly enough.
- The library will still see a timeout.
-
- Note that xterm mouse events are built up from
- character sequences received from the xterm. If your
- application makes heavy use of multiple-clicking, you
- may wish to lengthen this default value because the
- timeout applies to the composed multi-click event as
- well as the individual clicks.
-
- HOME Tells <STRONG>ncurses</STRONG> where your home directory is. That is
- where it may read and write auxiliary terminal
- descriptions:
-
- $HOME/.termcap
- $HOME/.terminfo
-
- LINES
- Like COLUMNS, specify the height of the screen in
- characters. See COLUMNS for a detailed description.
-
- MOUSE_BUTTONS_123
- This applies only to the OS/2 EMX port. It specifies
- the order of buttons on the mouse. OS/2 numbers a
- 3-button mouse inconsistently from other platforms:
-
- 1 = left
- 2 = right
- 3 = middle.
-
- This symbol lets you customize the mouse. The symbol
- must be three numeric digits 1-3 in any order, e.g.,
- 123 or 321. If it is not specified, <STRONG>ncurses</STRONG> uses
- 132.
-
- NCURSES_ASSUMED_COLORS
- Override the compiled-in assumption that the
- terminal's default colors are white-on-black (see
- <STRONG><A HREF="assume_default_colors.3x.html">assume_default_colors(3x)</A></STRONG>). You may set the
- foreground and background color values with this
- environment variable by proving a 2-element list:
- foreground,background. For example, to tell ncurses
- to not assume anything about the colors, set this to
- "-1,-1". To make it green-on-black, set it to "2,0".
- Any positive value from zero to the terminfo
- <STRONG>max_colors</STRONG> value is allowed.
-
- NCURSES_NO_PADDING
- Most of the terminal descriptions in the terminfo
- database are written for real "hardware" terminals.
- Many people use terminal emulators which run in a
- windowing environment and use curses-based
- applications. Terminal emulators can duplicate all
- of the important aspects of a hardware terminal, but
- they do not have the same limitations. The chief
- limitation of a hardware terminal from the standpoint
- of your application is the management of dataflow,
- i.e., timing. Unless a hardware terminal is
- interfaced into a terminal concentrator (which does
- flow control), it (or your application) must manage
- dataflow, preventing overruns. The cheapest solution
- (no hardware cost) is for your program to do this by
- pausing after operations that the terminal does
- slowly, such as clearing the display.
-
- As a result, many terminal descriptions (including
- the vt100) have delay times embedded. You may wish
- to use these descriptions, but not want to pay the
- performance penalty.
-
- Set the NCURSES_NO_PADDING symbol to disable all but
- mandatory padding. Mandatory padding is used as a
- part of special control sequences such as <EM>flash</EM>.
-
- NCURSES_NO_SETBUF
- Normally <STRONG>ncurses</STRONG> enables buffered output during
- terminal initialization. This is done (as in SVr4
- curses) for performance reasons. For testing
- purposes, both of <STRONG>ncurses</STRONG> and certain applications,
- this feature is made optional. Setting the
- NCURSES_NO_SETBUF variable disables output buffering,
- leaving the output in the original (usually line
- buffered) mode.
-
- NCURSES_TRACE
- During initialization, the <STRONG>ncurses</STRONG> debugging library
- checks the NCURSES_TRACE symbol. If it is defined,
- to a numeric value, <STRONG>ncurses</STRONG> calls the <STRONG>trace</STRONG> function,
- using that value as the argument.
-
- The argument values, which are defined in <STRONG>curses.h</STRONG>,
- provide several types of information. When running
- with traces enabled, your application will write the
- file <STRONG>trace</STRONG> to the current directory.
-
- TERM Denotes your terminal type. Each terminal type is
- distinct, though many are similar.
-
- TERMCAP
- If the <STRONG>ncurses</STRONG> library has been configured with
- <EM>termcap</EM> support, <STRONG>ncurses</STRONG> will check for a terminal's
- description in termcap form if it is not available in
- the terminfo database.
-
- The TERMCAP symbol contains either a terminal
- description (with newlines stripped out), or a file
- name telling where the information denoted by the
- TERM symbol exists. In either case, setting it
- directs <STRONG>ncurses</STRONG> to ignore the usual place for this
- information, e.g., /etc/termcap.
-
- TERMINFO
- Overrides the directory in which <STRONG>ncurses</STRONG> searches for
- your terminal description. This is the simplest, but
- not the only way to change the list of directories.
- The complete list of directories in order follows:
-
- - the last directory to which <STRONG>ncurses</STRONG> wrote, if any,
- is searched first.
-
- - the directory specified by the TERMINFO symbol
-
- - $HOME/.terminfo
-
- - directories listed in the TERMINFO_DIRS symbol
-
- - one or more directories whose names are configured
- and compiled into the ncurses library, e.g.,
- /usr/share/terminfo
-
- TERMINFO_DIRS
- Specifies a list of directories to search for
- terminal descriptions. The list is separated by
- colons (i.e., ":") on Unix, semicolons on OS/2 EMX.
- All of the terminal descriptions are in terminfo
- form, which makes a subdirectory named for the first
- letter of the terminal names therein.
-
- TERMPATH
- If TERMCAP does not hold a file name then <STRONG>ncurses</STRONG>
- checks the TERMPATH symbol. This is a list of
- filenames separated by spaces or colons (i.e., ":")
- on Unix, semicolons on OS/2 EMX. If the TERMPATH
- symbol is not set, <STRONG>ncurses</STRONG> looks in the files
- /etc/termcap, /usr/share/misc/termcap and
- $HOME/.termcap, in that order.
-
- The library may be configured to disregard the following
- variables when the current user is the superuser (root),
- or if the application uses setuid or setgid permissions:
- $TERMINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.