Add -m option to cron(8), overriding default mail recipient for cron mails,

unless explicitly provided by MAILTO= line in crontab.  This feature can be
useful in massive hosting environment, where most users do not care about
autogenerated mails.

Setting recipient to null string disables default mails at all.

Approved by:	yar
MFC after:	4 weeks

usr.sbin/cron/cron/cron.8

@@ -17,7 +17,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 17, 2007
+.Dd June 29, 2008
 .Dt CRON 8
 .Os
 .Sh NAME
@@ -27,6 +27,7 @@
 .Nm
 .Op Fl j Ar jitter
 .Op Fl J Ar rootjitter
+.Op Fl m Ar mailto
 .Op Fl s
 .Op Fl o
 .Op Fl x Ar debugflag Ns Op , Ns Ar ...
@@ -114,6 +115,23 @@ Enable time jitter for superuser jobs.
 The same as
 .Fl j
 except that it will affect jobs run by the superuser only.
+.It Fl m Ar mailto
+Overrides the default recipient for
+.Nm
+mail.
+Each
+.Xr crontab 5
+without
+.Ev MAILTO
+explicitly set will send mail to the
+.Ar mailto
+mailbox.
+Sending mail will be disabled by default if
+.Ar mailto
+set to a null string, usually specified in a shell as
+.Li ''
+or
+.Li \*q\*q .
 .It Fl s
 Enable special handling of situations when the GMT offset of the local
 timezone changes, such as the switches between the standard time and

usr.sbin/cron/cron/cron.c

@@ -53,7 +53,7 @@ usage() {
     char **dflags;
 
 	fprintf(stderr, "usage: cron [-j jitter] [-J rootjitter] "
-			"[-s] [-o] [-x debugflag[,...]]\n");
+			"[-m mailto] [-s] [-o] [-x debugflag[,...]]\n");
 	fprintf(stderr, "\ndebugflags: ");
 
         for(dflags = DebugFlagNames; *dflags; dflags++) {
@@ -443,7 +443,7 @@ parse_args(argc, argv)
 	int	argch;
 	char	*endp;
 
-	while ((argch = getopt(argc, argv, "j:J:osx:")) != -1) {
+	while ((argch = getopt(argc, argv, "j:J:m:osx:")) != -1) {
 		switch (argch) {
 		case 'j':
 			Jitter = strtoul(optarg, &endp, 10);
@@ -457,6 +457,9 @@ parse_args(argc, argv)
 				errx(ERROR_EXIT,
 				     "bad value for root jitter: %s", optarg);
 			break;
+		case 'm':
+			defmailto = optarg;
+			break;
 		case 'o':
 			dst_enabled = 0;
 			break;

usr.sbin/cron/cron/cron.h

@@ -268,7 +268,8 @@ char	*DowNames[] = {
 		NULL
 	};
 
-char	*ProgramName;
+char	*ProgramName,
+	*defmailto;
 int	LineNumber;
 unsigned Jitter,
 	RootJitter;
@@ -285,7 +286,8 @@ char	*DebugFlagNames[] = {	/* sync with #defines */
 extern	char	*copyright[],
 		*MonthNames[],
 		*DowNames[],
-		*ProgramName;
+		*ProgramName,
+		*defmailto;
 extern	int	LineNumber;
 extern unsigned	Jitter,
 		RootJitter;

usr.sbin/cron/cron/do_command.c

@@ -459,18 +459,14 @@ child_process(e, u)
 			/* get name of recipient.  this is MAILTO if set to a
 			 * valid local username; USER otherwise.
 			 */
-			if (mailto) {
-				/* MAILTO was present in the environment
+			if (mailto == NULL) {
+				/* MAILTO not present, set to USER,
+				 * unless globally overriden.
 				 */
-				if (!*mailto) {
-					/* ... but it's empty. set to NULL
-					 */
-					mailto = NULL;
-				}
-			} else {
-				/* MAILTO not present, set to USER.
-				 */
-				mailto = usernm;
+				if (defmailto)
+					mailto = defmailto;
+				else
+					mailto = usernm;
 			}
 
 			/* if we are supposed to be mailing, MAILTO will
@@ -478,7 +474,7 @@ child_process(e, u)
 			 * up the mail command and subjects and stuff...
 			 */
 
-			if (mailto) {
+			if (mailto && *mailto != '\0') {
 				register char	**env;
 				auto char	mailcmd[MAX_COMMAND];
 				auto char	hostname[MAXHOSTNAMELEN];