Make Remind adjust calendar to fit terminal.

man/remind.1

@@ -82,14 +82,19 @@ greater than 128, the color is considered "bright".
 .B \-w\fR\fIcol\fR[,\fIpad\fR[,\fIspc\fR]]]
 The \fB\-w\fR option specifies the output width, padding and spacing
 of the formatted calendar output.  \fICol\fR specifies the number of
-columns in the output device, and defaults to 80.  \fIPad\fR specifies
-how many lines to use to "pad" empty calendar boxes.  This defaults to
-5.  If you have many reminders on certain days that make your calendar
-too large to fit on a page, you can try reducing \fIpad\fR to make the
-empty boxes smaller.  \fISpc\fR specifies how many blank lines to leave
-between the day number and the first reminder entry.  It defaults to 1.
+columns in the output device.  If not specified, or specified as 0,
+it defaults to the larger of 71 or the actual width of your terminal,
+or to 80 if standard output is not a terminal.
 .RS
 .PP
+\fIPad\fR specifies how many lines
+to use to "pad" empty calendar boxes.  This defaults to 5.  If you
+have many reminders on certain days that make your calendar too large
+to fit on a page, you can try reducing \fIpad\fR to make the empty
+boxes smaller.  \fISpc\fR specifies how many blank lines to leave
+between the day number and the first reminder entry.  It defaults to
+1.
+.PP
 Any of \fIcol\fR, \fIpad\fR or \fIspc\fR can be omitted, providing you
 provide the correct number of commas.  Don't use any spaces in the option.
 .RE

src/calendar.c

@@ -16,6 +16,8 @@
 #include <ctype.h>
 
 #include <stdlib.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
 
 #ifdef REM_USE_WCHAR
 #include <wctype.h>
@@ -302,6 +304,27 @@ static void Colorize(CalEntry const *e)
   printf("%s", VT100Colors[bright][r][g][b]);
 }
 
+static int
+ComputeCalWidth(int x)
+{
+    struct winsize w;
+    if (x >= 71) {
+	/* Has been set with -w option */
+	return x;
+    }
+    if (!isatty(STDOUT_FILENO)) {
+	/* Output is not a TTY... assume 80 */
+	return 80;
+    }
+    if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &w) < 0) {
+	return 80;
+    }
+    if (w.ws_col < 71) {
+	return 80;
+    }
+    return w.ws_col;
+}
+
 /***************************************************************/
 /*                                                             */
 /*  ProduceCalendar                                            */
@@ -322,6 +345,8 @@ void ProduceCalendar(void)
     }
     ShouldCache = 1;
 
+    CalWidth = ComputeCalWidth(CalWidth);
+
     ColSpaces = (CalWidth - 9) / 7;
     CalWidth = 7*ColSpaces + 8;
 

src/globals.h

@@ -46,7 +46,7 @@ EXTERN  INIT(   int     DoPrefixLineNo, 0);
 EXTERN	INIT(	int	MondayFirst, 0);
 EXTERN	INIT(	int	Iterations, 1);
 EXTERN  INIT(   int     PsCal, 0);
-EXTERN  INIT(   int     CalWidth, 80);
+EXTERN  INIT(   int     CalWidth, -1);
 EXTERN  INIT(   int     CalWeeks, 0);
 EXTERN  INIT(   int     CalMonths, 0);
 EXTERN  INIT(	int 	Hush, 0);

src/init.c

@@ -430,7 +430,10 @@ void InitRemind(int argc, char const *argv[])
 	    case 'W':
 		if (*arg != ',') {
 		    PARSENUM(CalWidth, arg);
-		    if (CalWidth < 71) CalWidth = 71;
+		    if (CalWidth != 0 && CalWidth < 71) CalWidth = 71;
+		    if (CalWidth == 0) {
+			CalWidth = -1;
+		    }
 		}
 		if (*arg == ',') {
 		    arg++;