# curs_trace 3x

    curs_trace(3x)                                                  curs_trace(3x)

## NAME

           trace, _tracef, _traceattr, _traceattr2, _tracecchar_t, _tracecchar_t2,
           _tracechar, _tracechtype, _tracechtype2, _nc_tracebits, _tracedump,
           _tracemouse - curses debugging routines

## SYNOPSIS

           #include <curses.h>

           void trace(const unsigned int param);

           void _tracef(const char *format, ...);

           char *_traceattr(attr_t attr);
           char *_traceattr2(int buffer, chtype ch);
           char *_tracecchar_t(const cchar_t *string);
           char *_tracecchar_t2(int buffer, const cchar_t *string);
           char *_tracechar(int ch);
           char *_tracechtype(chtype ch);
           char *_tracechtype2(int buffer, chtype ch);

           void _tracedump(const char *label, WINDOW *win);
           char *_nc_tracebits(void);
           char *_tracemouse(const MEVENT *event);

## DESCRIPTION

           The  trace  routines  are  used for debugging the ncurses libraries, as
           well as applications which use the ncurses libraries.  These  functions
           are  normally available only with the debugging library e.g., libncurs-
           es_g.a, but may be compiled into any model (shared, static, profile) by
           defining  the  symbol  TRACE.   Additionally,  some  functions are only
           available with the wide-character configuration of the libraries.

### Functions

           The principal parts of this interface are

           o   trace, which selectively enables different tracing features, and

           o   _tracef, which writes formatted data to the trace file.

           Calling trace with a nonzero parameter creates the file  trace  in  the
           current  directory  for output.  If the file already exists, no tracing
           is done.

           The other functions either return a pointer to a string-area (allocated
           by the corresponding function), or return no value (such as _tracedump,
           which implements the screen dump for TRACE_UPDATE).  The caller  should
           not  free  these  strings, since the allocation is reused on successive
           calls.  To work around the problem of a single  string-area  per  func-
           tion,  some use a buffer-number parameter, telling the library to allo-
           cate additional string-areas.

### Trace Parameter

           The trace parameter is  formed  by  OR'ing  values  from  the  list  of
           TRACE_xxx definitions in <curses.h>.  These include:

           TRACE_DISABLE
                turn off tracing by passing a zero parameter.

                The  library flushes the output file, but retains an open file-de-
                scriptor to the trace file so that it can resume tracing later  if
                a nonzero parameter is passed to the trace function.

           TRACE_TIMES
                trace user and system times of updates.

           TRACE_TPUTS
                trace tputs(3x) calls.

           TRACE_UPDATE
                trace update actions, old & new screens.

           TRACE_MOVE
                trace cursor movement and scrolling.

           TRACE_CHARPUT
                trace all character outputs.

           TRACE_ORDINARY
                trace  all  update  actions.   The old and new screen contents are
                written to the trace file for each refresh.

           TRACE_CALLS
                trace all curses calls.  The parameters for each call are  traced,
                as well as return values.

           TRACE_VIRTPUT
                trace virtual character puts, i.e., calls to addch.

           TRACE_IEVENT
                trace low-level input processing, including timeouts.

           TRACE_BITS
                trace state of TTY control bits.

           TRACE_ICALLS
                trace internal/nested calls.

           TRACE_CCALLS
                trace per-character calls.

           TRACE_DATABASE
                trace read/write of terminfo/termcap data.

           TRACE_ATTRS
                trace changes to video attributes and colors.

           TRACE_MAXIMUM
                maximum trace level, enables all of the separate trace features.

           Some  tracing  features  are  enabled  whenever  the trace parameter is
           nonzero.  Some features overlap.  The specific  names  are  used  as  a
           guideline.

### Initialization

           These  functions  check  the NCURSES_TRACE environment variable, to set
           the tracing feature as if trace was called:

               filter, initscr, new_prescr, newterm, nofilter, restartterm,
               ripoffline, setupterm, slk_init, tgetent, use_env,
               use_extended_names, use_tioctl

### Command-line Utilities

           The command-line utilities such as  tic(1)  provide  a  verbose  option
           which  extends  the  set  of messages written using the trace function.
           Both of these (-v and trace) use the same variable (_nc_tracing), which
           determines the messages which are written.

           Because  the  command-line  utilities may call initialization functions
           such as setupterm, tgetent or use_extended_names, some of their  debug-
           ging  output may be directed to the trace file if the NCURSES_TRACE en-
           vironment variable is set:

           o   messages produced in the utility are written to the standard error.

           o   messages produced by the underlying library are written to trace.

           If ncurses is built without tracing, none of the latter  are  produced,
           and fewer diagnostics are provided by the command-line utilities.

## RETURN VALUE

           Routines  which return a value are designed to be used as parameters to
           the _tracef routine.

## PORTABILITY

           These functions are not part of the XSI interface.  Some  other  curses
           implementations  are  known to have similar, undocumented features, but
           they are not compatible with ncurses.

           A few functions are not provided when symbol versioning is used:

               _nc_tracebits, _tracedump, _tracemouse

## SEE ALSO

           curses(3x).

                                                                    curs_trace(3x)