Update vmstat usage for last-argument count/wait parameters

Correct the usage in both the manpage and in usage() to indicate
that the wait interval and repetition count may be given either
with the respective -w/-c arguments, or as the final positional
arguments. [0]

The corresponding code to implement the positional arguments has
been conditional on the (always-enabled) BACKWARD_COMPATIBILITY
macro since the original 4.4-lite import.  It's no longer reasonable
to remove the functionality, so remove the macro and conditional
instead.

Note that multiple disks may be given on the command line.

While here, sort arguments and apply minor mdoc fixes.

PR:		184755 [0]
Approved by:	hrs (mentor, src committer)

2 files changed, 26 insertions, 11 deletions

diff --git a/usr.bin/vmstat/vmstat.8 b/usr.bin/vmstat/vmstat.8
index f04cc42..4566ad2 100644
--- a/usr.bin/vmstat/vmstat.8
+++ b/usr.bin/vmstat/vmstat.8
@@ -28,7 +28,7 @@
 .\"	@(#)vmstat.8	8.1 (Berkeley) 6/6/93
 .\" $FreeBSD$
 .\"
-.Dd October 21, 2006
+.Dd August 8, 2014
 .Dt VMSTAT 8
 .Os
 .Sh NAME
@@ -38,9 +38,8 @@
 .Nm
 .\" .Op Fl fimst
 .Op Fl afHhimPsz
-.Op Fl c Ar count
 .Op Fl M Ar core Op Fl N Ar system
-.Op Fl w Ar wait
+.Op Fl c Ar count
 .Op Fl n Ar devs
 .Oo
 .Fl p
@@ -48,7 +47,9 @@
 .Ar type , if , pass
 .Sm on
 .Oc
-.Op Ar disks
+.Op Fl w Ar wait
+.Op Ar disks ...
+.Op wait Op count
 .Sh DESCRIPTION
 The
 .Nm
@@ -91,10 +92,12 @@ and
 system calls since system startup, and the number of pages of virtual memory
 involved in each.
 .It Fl h
-Changes memory columns into more easily human readable form.  Default if
+Changes memory columns into more easily human readable form.
+The default if
 standard output is a terminal device.
 .It Fl H
-Changes memory columns into straight numbers.  Default if standard output
+Changes memory columns into straight numbers.
+The default if standard output
 is not a terminal device (such as a script).
 .It Fl i
 Report on the number of interrupts taken by each device since system
@@ -214,6 +217,21 @@ Report on memory used by the kernel zone allocator,
 by zone.
 .El
 .Pp
+The
+.Ar wait
+and
+.Ar count
+arguments may be given after their respective flags at any point
+on the command line before the
+.Ar disks
+argument(s), or without their flags, as the final argument(s).
+The latter form is accepted for backwards compatibility, but it is
+preferred to use the forms with
+.Fl w
+and
+.Fl c
+to avoid ambiguity.
+.Pp
 By default,
 .Nm
 displays the following information:
diff --git a/usr.bin/vmstat/vmstat.c b/usr.bin/vmstat/vmstat.c
index 67f438e..227f3c2 100644
--- a/usr.bin/vmstat/vmstat.c
+++ b/usr.bin/vmstat/vmstat.c
@@ -299,15 +299,12 @@ retry_nlist:
 		argv = getdrivedata(argv);
 	}
 
-#define	BACKWARD_COMPATIBILITY
-#ifdef	BACKWARD_COMPATIBILITY
 	if (*argv) {
 		f = atof(*argv);
 		interval = f * 1000;
 		if (*++argv)
 			reps = atoi(*argv);
 	}
-#endif
 
 	if (interval) {
 		if (!reps)
@@ -1360,7 +1357,7 @@ static void
 usage(void)
 {
 	(void)fprintf(stderr, "%s%s",
-		"usage: vmstat [-afHhimPsz] [-c count] [-M core [-N system]] [-w wait]\n",
-		"              [-n devs] [-p type,if,pass] [disks]\n");
+		"usage: vmstat [-afHhimPsz] [-M core [-N system]] [-c count] [-n devs]\n",
+		"              [-p type,if,pass] [-w wait] [disks] [wait [count]]\n");
 	exit(1);
 }