- initscr is normally the first curses routine to call when
- initializing a program. A few special routines sometimes
- need to be called before it; these are slk_init, filter,
- ripoffline, use_env. For multiple-terminal applications,
- newterm may be called before initscr.
-
- The initscr code determines the terminal type and initial-
- izes all curses data structures. initscr also causes the
- first call to refresh to clear the screen. If errors oc-
- cur, initscr writes an appropriate error message to stan-
- dard error and exits; otherwise, a pointer is returned to
- stdscr.
-
- A program that outputs to more than one terminal should
- use the newterm routine for each terminal instead of
- initscr. A program that needs to inspect capabilities, so
- it can continue to run in a line-oriented mode if the ter-
- minal cannot support a screen-oriented program, would also
- use newterm. The routine newterm should be called once
- for each terminal. It returns a variable of type SCREEN*
- which should be saved as a reference to that terminal.
- newterm's arguments are
+
+ initscr is normally the first curses routine to call when initializing
+ a program. A few special routines sometimes need to be called before
+ it; these are slk_init(3x), filter, ripoffline, use_env. For multiple-
+ terminal applications, newterm may be called before initscr.
+
+ The initscr code determines the terminal type and initializes all curs-
+ es data structures. initscr also causes the first call to refresh(3x)
+ to clear the screen. If errors occur, initscr writes an appropriate
+ error message to standard error and exits; otherwise, a pointer is re-
+ turned to stdscr.
+
+
+
+ A program that outputs to more than one terminal should use the newterm
+ routine for each terminal instead of initscr. A program that needs to
+ inspect capabilities, so it can continue to run in a line-oriented mode
+ if the terminal cannot support a screen-oriented program, would also
+ use newterm. The routine newterm should be called once for each termi-
+ nal. It returns a variable of type SCREEN* which should be saved as a
+ reference to that terminal. newterm's arguments are
o the type of the terminal to be used in place of $TERM,
@@ -96,101 +93,183 @@
If the type parameter is NULL, $TERM will be used.
- The program must also call endwin for each terminal being
- used before exiting from curses. If newterm is called
- more than once for the same terminal, the first terminal
- referred to must be the last one for which endwin is
- called.
- A program should always call endwin before exiting or es-
- caping from curses mode temporarily. This routine
+
+ The program must also call endwin for each terminal being used before
+ exiting from curses. If newterm is called more than once for the same
+ terminal, the first terminal referred to must be the last one for which
+ endwin is called.
- o restores tty modes,
+ A program should always call endwin before exiting or escaping from
+ curses mode temporarily. This routine
- o moves the cursor to the lower left-hand corner of the
- screen and
+ o resets colors to correspond with the default color pair 0,
- o resets the terminal into the proper non-visual mode.
+ o moves the cursor to the lower left-hand corner of the screen,
- Calling refresh or doupdate after a temporary escape caus-
- es the program to resume visual mode.
+ o clears the remainder of the line so that it uses the default col-
+ ors,
- The isendwin routine returns TRUE if endwin has been
- called without any subsequent calls to wrefresh, and FALSE
- otherwise.
+ o sets the cursor to normal visibility (see curs_set(3x)),
- The set_term routine is used to switch between different
- terminals. The screen reference new becomes the new cur-
- rent terminal. The previous terminal is returned by the
- routine. This is the only routine which manipulates
- SCREEN pointers; all other routines affect only the cur-
- rent terminal.
+ o stops cursor-addressing mode using the exit_ca_mode terminal capa-
+ bility,
- The delscreen routine frees storage associated with the
- SCREEN data structure. The endwin routine does not do
- this, so delscreen should be called after endwin if a par-
- ticular SCREEN is no longer needed.
+ o restores tty modes (see reset_shell_mode(3x)).
+ Calling refresh(3x) or doupdate(3x) after a temporary escape causes the
+ program to resume visual mode.
+
+
+
+ The set_term routine is used to switch between different terminals.
+ The screen reference new becomes the new current terminal. The previ-
+ ous terminal is returned by the routine. This is the only routine
+ which manipulates SCREEN pointers; all other routines affect only the
+ current terminal.
-
-
RETURN VALUE
- endwin returns the integer ERR upon failure and OK upon
- successful completion.
+
+
+ The delscreen routine frees storage associated with the SCREEN data
+ structure. The endwin routine does not do this, so delscreen should be
+ called after endwin if a particular SCREEN is no longer needed.
+
+
+
+ endwin returns the integer ERR upon failure and OK upon successful com-
+ pletion.
Routines that return pointers always return NULL on error.
- X/Open defines no error conditions. In this implementa-
- tion
+ X/Open defines no error conditions. In this implementation
- oendwin returns an error if the terminal was not ini-
- tialized.
+ oendwin returns an error if the terminal was not initialized.
- onewterm returns an error if it cannot allocate the da-
- ta structures for the screen, or for the top-level
- windows within the screen, i.e., curscr, newscr, or
- stdscr.
+ onewterm returns an error if it cannot allocate the data structures
+ for the screen, or for the top-level windows within the screen,
+ i.e., curscr, newscr, or stdscr.
oset_term returns no error.
-
+ These functions were described in the XSI Curses standard, Issue 4. As
+ of 2015, the current document is X/Open Curses, Issue 7.
-
-
PORTABILITY
- These functions are described in the XSI Curses standard,
- Issue 4. It specifies that portable applications must not
- call initscr more than once.
+
+ X/Open specifies that portable applications must not call initscr more
+ than once:
- Old versions of curses, e.g., BSD 4.4, may have returned a
- null pointer from initscr when an error is detected,
- rather than exiting. It is safe but redundant to check
- the return value of initscr in XSI Curses.
+ o The portable way to use initscr is once only, using refresh (see
+ curs_refresh(3x)) to restore the screen after endwin.
- If the TERM variable is missing or empty, initscr uses the
- value "unknown", which normally corresponds to a terminal
- entry with the generic (gn) capability. Generic entries
- are detected by curs_terminfo(3x) and cannot be used for full-
- screen operation. Other implementations may handle a
- missing/empty TERM variable differently.
+ o This implementation allows using initscr after endwin.
+ Old versions of curses, e.g., BSD 4.4, may have returned a null pointer
+ from initscr when an error is detected, rather than exiting. It is
+ safe but redundant to check the return value of initscr in XSI Curses.
-
+ If the TERM variable is missing or empty, initscr uses the value "un-
+ known", which normally corresponds to a terminal entry with the generic
+ (gn) capability. Generic entries are detected by setupterm (see
+ curs_terminfo(3x)) and cannot be used for full-screen operation. Other
+ implementations may handle a missing/empty TERM variable differently.
+
+
+
+ Quoting from X/Open Curses, section 3.1.1:
+
+ Cursesimplementationsmayprovideforspecialhandlingofthe
+ SIGINT,SIGQUITandSIGTSTPsignalsiftheirdispositionis
+ SIG_DFLatthetimeinitscriscalled...
+
+ Anyspecialhandlingforthesesignalsmayremainineffectfor
+ thelifeoftheprocessoruntiltheprocesschangesthedisposi-
+ tionofthesignal.
+
+ NoneoftheCursesfunctionsarerequiredtobesafewithrespect
+ tosignals ...
+
+ This implementation establishes signal handlers during initialization,
+ e.g., initscr or newterm. Applications which must handle these signals
+ should set up the corresponding handlers after initializing the li-
+ brary:
+
+ SIGINT
+ The handler attempts to cleanup the screen on exit. Although it
+ usually works as expected, there are limitations:
+
+ o Walking the SCREEN list is unsafe, since all list management
+ is done without any signal blocking.
+
+ o On systems which have REENTRANT turned on, set_term uses func-
+ tions which could deadlock or misbehave in other ways.
+
+ oendwin calls other functions, many of which use stdio or other
+ library functions which are clearly unsafe.
+
+ SIGTERM
+ This uses the same handler as SIGINT, with the same limitations.
+ It is not mentioned in X/Open Curses, but is more suitable for
+ this purpose than SIGQUIT (which is used in debugging).
+
+ SIGTSTP
+ This handles the stop signal, used in job control. When resuming
+ the process, this implementation discards pending input with
+ flushinput (see curs_util(3x)), and repaints the screen assuming
+ that it has been completely altered. It also updates the saved
+ terminal modes with def_shell_mode (see curs_kernel(3x)).
+
+ SIGWINCH
+ This handles the window-size changes which were ignored in the
+ standardization efforts. The handler sets a (signal-safe) vari-
+ able which is later tested in wgetch (see curs_getch(3x)). If
+ keypad has been enabled for the corresponding window, wgetch re-
+ turns the key symbol KEY_RESIZE. At the same time, wgetch calls
+ resizeterm to adjust the standard screen stdscr, and update other
+ data such as LINES and COLS.
+
+
+