ncurses 6.5 - patch 20240622

[ncurses.git] / man / curs_initscr.3x

diff --git a/man/curs_initscr.3x b/man/curs_initscr.3x
index 83e459dd28826440166713de633f49a192e30d5b..1e30604a7afff180fa535a2a1c2664bee1bcbe44 100644 (file)
--- a/man/curs_initscr.3x
+++ b/man/curs_initscr.3x
@@ -1,5 +1,6 @@
 .\"***************************************************************************
 .\"***************************************************************************

-.\" Copyright (c) 1998-2017,2018 Free Software Foundation, Inc.              *
+.\" Copyright 2018-2023,2024 Thomas E. Dickey                                *
+.\" Copyright 1998-2016,2017 Free Software Foundation, Inc.                  *

 .\"                                                                          *
 .\" Permission is hereby granted, free of charge, to any person obtaining a  *
 .\" copy of this software and associated documentation files (the            *
 .\"                                                                          *
 .\" Permission is hereby granted, free of charge, to any person obtaining a  *
 .\" copy of this software and associated documentation files (the            *


@@ -26,87 +27,93 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"

-.\" $Id: curs_initscr.3x,v 1.30 2018/04/07 20:54:12 tom Exp $
-.TH curs_initscr 3X ""
+.\" $Id: curs_initscr.3x,v 1.75 2024/06/08 20:34:23 tom Exp $
+.TH curs_initscr 3X 2024-06-08 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
+.ie \n(.g \{\
+.ds `` \(lq
+.ds '' \(rq
+.\}
+.el \{\
+.ie t .ds `` ``
+.el   .ds `` ""
+.ie t .ds '' ''
+.el   .ds '' ""
+.\}
+.

 .de bP
 .ie n  .IP \(bu 4
 .el    .IP \(bu 2
 ..
 .de bP
 .ie n  .IP \(bu 4
 .el    .IP \(bu 2
 ..

-.ie \n(.g .ds `` \(lq
-.el       .ds `` ``
-.ie \n(.g .ds '' \(rq
-.el       .ds '' ''
-.na
-.hy 0

 .SH NAME
 .SH NAME

-\fBinitscr\fR,
-\fBnewterm\fR,
-\fBendwin\fR,
-\fBisendwin\fR,
-\fBset_term\fR,
-\fBdelscreen\fR \- \fBcurses\fR screen initialization and manipulation routines
-.ad
-.hy
+\fB\%initscr\fP,
+\fB\%newterm\fP,
+\fB\%endwin\fP,
+\fB\%isendwin\fP,
+\fB\%set_term\fP,
+\fB\%delscreen\fP \-
+initialize, manipulate, or tear down \fIcurses\fR terminal interface

 .SH SYNOPSIS
 .SH SYNOPSIS

-\fB#include <curses.h>\fR
-.sp
-\fBWINDOW *initscr(void);\fR
-.br
-\fBint endwin(void);\fR
-.br
-\fBbool isendwin(void);\fR
-.br
-\fBSCREEN *newterm(const char *\fP\fItype\fP\fB, FILE *\fP\fIoutfd\fP\fB, FILE *\fP\fIinfd\fP\fB);\fR
-.br
-\fBSCREEN *set_term(SCREEN *\fP\fInew\fP\fB);\fR
-.br
-\fBvoid delscreen(SCREEN* \fP\fIsp\fP\fB);\fR
-.br
+.nf
+\fB#include <curses.h>
+.PP
+\fBWINDOW *initscr(void);
+\fBint endwin(void);
+.PP
+\fBbool isendwin(void);
+.PP
+\fBSCREEN *newterm(const char *\fItype\fP, FILE *\fIoutf\fP, FILE *\fIinf\fP);
+\fBSCREEN *set_term(SCREEN *\fInew\fP);
+\fBvoid delscreen(SCREEN* \fIsp\fP);
+.fi

 .SH DESCRIPTION
 .SS initscr
 .SH DESCRIPTION
 .SS initscr

-\fBinitscr\fR is normally the first \fBcurses\fR routine to call when
+\fBinitscr\fP is normally the first \fBcurses\fP routine to call when

 initializing a program.
 A few special routines sometimes need to be called before it;
 initializing a program.
 A few special routines sometimes need to be called before it;

-these are \fBslk_init\fR(3X), \fBfilter\fR, \fBripoffline\fR,
-\fBuse_env\fR.
+these are \fBslk_init\fP(3X), \fBfilter\fP, \fBripoffline\fP,
+\fBuse_env\fP.

 For multiple-terminal applications,
 For multiple-terminal applications,

-\fBnewterm\fR may be called before \fBinitscr\fR.
+\fBnewterm\fP may be called before \fBinitscr\fP.

 .PP
 .PP

-The initscr code determines the terminal type and initializes all \fBcurses\fR
+The initscr code determines the terminal type and initializes all \fBcurses\fP

 data structures.
 data structures.

-\fBinitscr\fR also causes the first call to \fBrefresh\fR(3X) to clear the screen.
-If errors occur, \fBinitscr\fR writes an appropriate error
+\fBinitscr\fP also causes the first call to \fBrefresh\fP(3X)
+to clear the screen.
+If errors occur, \fBinitscr\fP writes an appropriate error

 message to standard error and exits;
 message to standard error and exits;

-otherwise, a pointer is returned to \fBstdscr\fR.
+otherwise, a pointer is returned to \fBstdscr\fP.

 .SS newterm
 .SS newterm

-.PP
-A program that outputs to more than one terminal should use the \fBnewterm\fR
-routine for each terminal instead of \fBinitscr\fR.
+A program that outputs to more than one terminal should use the \fBnewterm\fP
+routine for each terminal instead of \fBinitscr\fP.

 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
 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

-\fBnewterm\fR.
-The routine \fBnewterm\fR should be called once for each terminal.
-It returns a variable of type \fBSCREEN *\fR which should be saved
+\fBnewterm\fP.
+.PP
+The routine \fBnewterm\fP should be called once for each terminal.
+It returns a variable of type \fISCREEN *\fP which should be saved

 as a reference to that terminal.
 \fBnewterm\fP's arguments are
 .bP
 as a reference to that terminal.
 \fBnewterm\fP's arguments are
 .bP

-the \fItype\fR of the terminal to be used in place of \fB$TERM\fR,
+the \fItype\fP of the terminal to be used in place of \fB$TERM\fP,

 .bP
 .bP

-a file pointer for output to the terminal, and
+an output stream connected to the terminal, and

 .bP
 .bP

-another file pointer for input from the terminal
+an input stream connected to the terminal

 .PP
 .PP

-If the \fItype\fR parameter is \fBNULL\fR, \fB$TERM\fR will be used.
-.SS endwin
+If the \fItype\fP parameter is \fBNULL\fP, \fB$TERM\fP will be used.

 .PP
 .PP

+The file descriptor of the output stream is passed to \fBsetupterm\fP(3X),
+which returns a pointer to a \fI\%TERMINAL\fP structure.
+\fBnewterm\fP's return value holds a pointer to the \fI\%TERMINAL\fP structure.
+.SS endwin

 The program must also call
 The program must also call

-\fBendwin\fR for each terminal being used before exiting from \fBcurses\fR.
-If \fBnewterm\fR is called more than once for the same terminal, the first
-terminal referred to must be the last one for which \fBendwin\fR is called.
+\fBendwin\fP for each terminal being used before exiting from \fBcurses\fP.
+If \fBnewterm\fP is called more than once for the same terminal, the first
+terminal referred to must be the last one for which \fBendwin\fP is called.

 .PP
 .PP

-A program should always call \fBendwin\fR before exiting or escaping from
-\fBcurses\fR mode temporarily.
+A program should always call \fBendwin\fP before exiting or escaping from
+\fBcurses\fP mode temporarily.

 This routine
 .bP
 resets colors to correspond with the default color pair 0,
 This routine
 .bP
 resets colors to correspond with the default color pair 0,


@@ -121,40 +128,50 @@ stops cursor-addressing mode using the \fIexit_ca_mode\fP terminal capability,
 .bP
 restores tty modes (see \fBreset_shell_mode\fP(3X)).
 .PP
 .bP
 restores tty modes (see \fBreset_shell_mode\fP(3X)).
 .PP

-Calling \fBrefresh\fR(3X) or \fBdoupdate\fR(3X) after a
+Calling \fBrefresh\fP(3X) or \fBdoupdate\fP(3X) after a

 temporary escape causes the program to resume visual mode.
 .SS isendwin
 temporary escape causes the program to resume visual mode.
 .SS isendwin

-.PP
-The \fBisendwin\fR routine returns \fBTRUE\fR if \fBendwin\fR has been
-called without any subsequent calls to \fBwrefresh\fR,
-and \fBFALSE\fR otherwise.
+The \fBisendwin\fP routine returns \fBTRUE\fP if \fBendwin\fP has been
+called without any subsequent calls to \fBwrefresh\fP,
+and \fBFALSE\fP otherwise.

 .SS set_term
 .SS set_term

-.PP
-The \fBset_term\fR routine is used to switch between different terminals.
-The screen reference \fBnew\fR becomes the new current terminal.
+The \fBset_term\fP routine is used to switch between different terminals.
+The screen reference \fInew\fP becomes the new current terminal.

 The previous terminal is returned by the routine.
 The previous terminal is returned by the routine.

-This is the only routine which manipulates \fBSCREEN\fR pointers;
+This is the only routine which manipulates \fISCREEN\fP pointers;

 all other routines affect only the current terminal.
 .SS delscreen
 all other routines affect only the current terminal.
 .SS delscreen

-.PP
-The \fBdelscreen\fR routine frees storage associated with the
-\fBSCREEN\fR data structure.
-The \fBendwin\fR routine does not do
-this, so \fBdelscreen\fR should be called after \fBendwin\fR if a
-particular \fBSCREEN\fR is no longer needed.
+The \fBdelscreen\fP routine frees storage associated with the
+\fISCREEN\fP data structure.
+The \fBendwin\fP routine does not do
+this, so \fBdelscreen\fP should be called after \fBendwin\fP if a
+particular \fISCREEN\fP is no longer needed.

 .SH RETURN VALUE
 .SH RETURN VALUE

-\fBendwin\fR returns the integer \fBERR\fR upon failure and \fBOK\fR
+\fBendwin\fP returns the integer \fBERR\fP upon failure and \fBOK\fP

 upon successful completion.
 .PP
 upon successful completion.
 .PP

-Routines that return pointers always return \fBNULL\fR on error.
+Routines that return pointers always return \fBNULL\fP on error.

 .PP
 X/Open defines no error conditions.
 In this implementation
 .bP
 .PP
 X/Open defines no error conditions.
 In this implementation
 .bP

-\fBendwin\fP returns an error if the terminal was not initialized.
+\fBendwin\fP returns
+.B ERR
+if
+.RS
+.bP
+the terminal was not initialized, or
+.bP
+\fBendwin\fP is called more than once without updating the screen, or
+.bP
+\fBreset_shell_mode\fP(3X) return
+.BR ERR "."
+.RE

 .bP
 \fBnewterm\fP
 .bP
 \fBnewterm\fP

-returns an error if it cannot allocate the data structures for the screen,
+returns
+.B ERR
+if it cannot allocate the data structures for the screen,

 or for the top-level windows within the screen,
 i.e.,
 \fBcurscr\fP, \fBnewscr\fP, or \fBstdscr\fP.
 or for the top-level windows within the screen,
 i.e.,
 \fBcurscr\fP, \fBnewscr\fP, or \fBstdscr\fP.


@@ -162,45 +179,95 @@ i.e.,
 \fBset_term\fP
 returns no error.
 .SH PORTABILITY
 \fBset_term\fP
 returns no error.
 .SH PORTABILITY

-These functions were described in the XSI Curses standard, Issue 4.
+These functions were described in X/Open Curses, Issue 4.

 As of 2015, the current document is X/Open Curses, Issue 7.
 .SS Differences
 As of 2015, the current document is X/Open Curses, Issue 7.
 .SS Differences

-X/Open specifies that portable applications must not
-call \fBinitscr\fR more than once:
+X/Open Curses specifies that portable applications must not
+call \fBinitscr\fP more than once:

 .bP
 The portable way to use \fBinitscr\fP is once only,
 .bP
 The portable way to use \fBinitscr\fP is once only,

-using \fBrefresh\fP (see curs_refresh(3X)) to restore the screen after \fBendwin\fP.
+using \fB\%refresh\fP(3X)
+to restore the screen after \fBendwin\fP.

 .bP
 This implementation allows using \fBinitscr\fP after \fBendwin\fP.
 .PP
 .bP
 This implementation allows using \fBinitscr\fP after \fBendwin\fP.
 .PP

-Old versions of curses, e.g., BSD 4.4, may have returned a null pointer
-from \fBinitscr\fR when an error is detected, rather than exiting.
-It is safe but redundant to check the return value of \fBinitscr\fR
-in XSI Curses.
-.SS Unset TERM Variable
+Old versions of curses, e.g., BSD 4.4, would return a null pointer
+from \fBinitscr\fP when an error is detected, rather than exiting.
+It is safe but redundant to check the return value of \fBinitscr\fP
+in X/Open Curses.
+.PP
+Calling \fBendwin\fP does not dispose of the memory allocated in \fBinitscr\fP
+or \fBnewterm\fP.
+Deleting a \fISCREEN\fP provides a way to do this:
+.bP
+X/Open Curses does not say what happens to \fI\%WINDOW\fPs when \fBdelscreen\fP
+\*(``frees storage associated with the \fISCREEN\fP\*(''
+nor does the SVr4 documentation help,
+adding that it should be called after \fBendwin\fP if a \fISCREEN\fP
+is no longer needed.
+.bP
+However, \fI\%WINDOW\fPs are implicitly associated with a \fISCREEN\fP.
+so that it is reasonable to expect \fBdelscreen\fP to deal with these.
+.bP
+SVr4 curses deletes the standard \fI\%WINDOW\fP structures
+\fBstdscr\fP and \fBcurscr\fP as well as a work area \fBnewscr\fP.
+SVr4 curses ignores other windows.
+.bP
+Since version 4.0 (1996),
+\fI\%ncurses\fP has maintained a list of all windows for each screen,
+using that information to delete those windows when \fBdelscreen\fP is called.
+.bP
+NetBSD copied this feature of \fI\%ncurses\fP in 2001.
+PDCurses follows the SVr4 model,
+deleting only the standard \fI\%WINDOW\fP structures.
+.SS "High-level versus Low-level"
+Different implementations may disagree regarding the level of some functions.
+For example, \fISCREEN\fP (returned by \fBnewterm\fP) and
+\fI\%TERMINAL\fP (returned by \fBsetupterm\fP(3X)) hold file descriptors for
+the output stream.
+If an application switches screens using \fBset_term\fR,
+or switches terminals using \fBset_curterm\fP(3X),
+applications which use the output file descriptor can have different
+behavior depending on which structure holds the corresponding descriptor.

 .PP
 .PP

-If the TERM variable is missing or empty, \fBinitscr\fP uses the
+For example
+.bP
+NetBSD's \fBbaudrate\fP(3X) function uses the descriptor in \fI\%TERMINAL\fP.
+\fI\%ncurses\fP and SVr4 use the descriptor in \fISCREEN\fP.
+.bP
+NetBSD and \fI\%ncurses\fP use the descriptor
+in \fI\%TERMINAL\fP
+for terminal I/O modes,
+e.g.,
+\fBdef_shell_mode\fP(3X),
+\fBdef_prog_mode\fP(3X).
+SVr4 curses uses the descriptor in \fISCREEN\fP.
+.SS "Unset \fITERM\fP Variable"
+If the \fITERM\fP variable is missing or empty, \fBinitscr\fP uses the

 value \*(``unknown\*('',
 which normally corresponds to a terminal entry with the \fIgeneric\fP
 (\fIgn\fP) capability.
 value \*(``unknown\*('',
 which normally corresponds to a terminal entry with the \fIgeneric\fP
 (\fIgn\fP) capability.

-Generic entries are detected by \fBsetupterm\fP (see curs_terminfo(3X)) and cannot be
-used for full-screen operation.
-Other implementations may handle a missing/empty TERM variable differently.
-.SS Signal Handlers
-.PP
-Quoting from X/Open Curses, section 3.1.1:
+Generic entries are detected by \fBsetupterm\fP(3X)
+and cannot be used for full-screen operation.
+Other implementations may handle
+a missing/empty \fITERM\fP variable differently.
+.SS "Signal Handlers"
+Quoting from X/Open Curses Issue 7, section 3.1.1:

 .RS 5
 .PP
 .RS 5
 .PP

-\fICurses implementations may provide for special handling of the \fBSIGINT\fP,
-\fBSIGQUIT\fP and \fBSIGTSTP\fP signals
-if their disposition is \fBSIG_DFL\fP at the time
-\fBinitscr\fP is called \fP...
+Curses implementations may provide for special handling of the
+\%SIGINT,
+\%SIGQUIT,
+and \%SIGTSTP signals if their disposition is \%SIG_DFL at the time
+.I \%initscr
+is called.\|.\|.

 .PP
 .PP

-\fIAny special handling for these signals may remain in effect for the
+Any special handling for these signals may remain in effect for the

 life of the process or until the process changes the disposition of
 life of the process or until the process changes the disposition of

-the signal.\fP
+the signal.

 .PP
 .PP

-\fINone of the Curses functions are required to be safe with respect to signals \fP...
+None of the Curses functions are required to be safe
+with respect to signals.\|.\|.

 .RE
 .PP
 This implementation establishes signal handlers during initialization,
 .RE
 .PP
 This implementation establishes signal handlers during initialization,


@@ -209,18 +276,19 @@ Applications which must handle these signals should set up the corresponding
 handlers \fIafter\fP initializing the library:
 .TP 5
 .B SIGINT
 handlers \fIafter\fP initializing the library:
 .TP 5
 .B SIGINT

-The handler \fIattempts\fP to cleanup the screen on exit.
+The handler \fIattempts\fP to clean up the screen on exit.

 Although it \fIusually\fP works as expected, there are limitations:
 .RS 5
 .bP
 Although it \fIusually\fP works as expected, there are limitations:
 .RS 5
 .bP

-Walking the \fBSCREEN\fP list is unsafe, since all list management
+Walking the \fISCREEN\fP list is unsafe, since all list management

 is done without any signal blocking.
 .bP
 On systems which have \fBREENTRANT\fP turned on, \fBset_term\fP uses
 functions which could deadlock or misbehave in other ways.
 .bP
 is done without any signal blocking.
 .bP
 On systems which have \fBREENTRANT\fP turned on, \fBset_term\fP uses
 functions which could deadlock or misbehave in other ways.
 .bP

-\fBendwin\fP calls other functions, many of which use stdio or
-other library functions which are clearly unsafe.
+\fBendwin\fP calls other functions,
+many of which use \fI\%stdio\fP(3) or other library functions which are
+clearly unsafe.

 .RE
 .TP 5
 .B SIGTERM
 .RE
 .TP 5
 .B SIGTERM


@@ -231,25 +299,39 @@ purpose than \fBSIGQUIT\fP (which is used in debugging).
 .B SIGTSTP
 This handles the \fIstop\fP signal, used in job control.
 When resuming the process, this implementation discards pending
 .B SIGTSTP
 This handles the \fIstop\fP signal, used in job control.
 When resuming the process, this implementation discards pending

-input with \fBflushinput\fP (see curs_util(3X)), and repaints the screen
+input with \fB\%flushinp\fP(3X), and repaints the screen

 assuming that it has been completely altered.
 assuming that it has been completely altered.

-It also updates the saved terminal modes with \fBdef_shell_mode\fP (see curs_kernel(3X)).
+It also updates the saved terminal modes with
+\fB\%def_shell_mode\fP(3X).

 .TP 5
 .B SIGWINCH
 This handles the window-size changes which were ignored in
 the standardization efforts.
 The handler sets a (signal-safe) variable
 .TP 5
 .B SIGWINCH
 This handles the window-size changes which were ignored in
 the standardization efforts.
 The handler sets a (signal-safe) variable

-which is later tested in \fBwgetch\fP (see curs_getch(3X)).
-If \fBkeypad\fP has been enabled for the corresponding window,
-\fBwgetch\fP returns the key symbol \fBKEY_RESIZE\fP.
-At the same time, \fBwgetch\fP calls \fBresizeterm\fP to adjust the
+that is later tested by \fB\%wgetch\fP(3X) and \fB\%wget_wch\fP(3X).
+.RS
+.bP
+.B \%wgetch
+returns the key code
+.BR \%KEY_RESIZE "."
+.bP
+.B \%wget_wch
+returns
+.B \%KEY_CODE_YES
+and sets its
+.I wch
+parameter to
+.BR \%KEY_RESIZE "."
+.RE
+.IP
+At the same time, \fI\%ncurses\fP calls \fBresizeterm\fP to adjust the

 standard screen \fBstdscr\fP,
 and update other data such as \fBLINES\fP and \fBCOLS\fP.
 .SH SEE ALSO
 standard screen \fBstdscr\fP,
 and update other data such as \fBLINES\fP and \fBCOLS\fP.
 .SH SEE ALSO

-\fBcurses\fR(3X),
-\fBcurs_kernel\fR(3X),
-\fBcurs_refresh\fR(3X),
-\fBcurs_slk\fR(3X),
-\fBcurs_terminfo\fR(3X),
-\fBcurs_util\fR(3X),
-\fBcurs_variables\fR(3X).
+\fB\%curses\fP(3X),
+\fB\%curs_kernel\fP(3X),
+\fB\%curs_refresh\fP(3X),
+\fB\%curs_slk\fP(3X),
+\fB\%curs_terminfo\fP(3X),
+\fB\%curs_util\fP(3X),
+\fB\%curs_variables\fP(3X)