Try to make sysctl options slightly more orthogonal:

 - introduce a -o option that displays opaque variables.
 - introduce a -x option that displays opaque variables in full.
 - deprecate -A in favor of -ao and -X in favor of -ax.
 - remove -A and -X from usage() and SYNOPSIS (but not from DESCRIPTION).
 - ignore -a if one or more variables were listed on the command line.
 - deprecate -w, it is not needed to determine the user's intentions.
 - some language and style cleanup in the man page.

This commit should not break any existing scripts.

MFC after:	4 weeks

2 files changed, 70 insertions, 63 deletions

diff --git a/sbin/sysctl/sysctl.8 b/sbin/sysctl/sysctl.8
index 9868eba..c5ca4b7 100644
--- a/sbin/sysctl/sysctl.8
+++ b/sbin/sysctl/sysctl.8
@@ -40,64 +40,68 @@
 .Nd get or set kernel state
 .Sh SYNOPSIS
 .Nm
-.Op Fl bNn
-.Ar name ...
+.Op Fl bNnox
+.Ar name Ns Op = Ns Ar value
+.Ar ...
 .Nm
-.Op Fl bNn
-.Fl w
-.Ar name Ns = Ns Ar value ...
-.Nm
-.Op Fl bNn
-.Fl aAX
+.Op Fl bNnox
+.Fl a
 .Sh DESCRIPTION
 The
 .Nm
-utility retrieves kernel state and allows processes with
-appropriate privilege to set kernel state.
-The state to be retrieved or set is described using a
-``Management Information Base'' (``MIB'') style name,
-described as a dotted set of components.
+utility retrieves kernel state and allows processes with appropriate
+privilege to set kernel state.
+The state to be retrieved or set is described using a ``Management
+Information Base'' (``MIB'') style name, described as a dotted set of
+components.
 .Pp
 The following options are available:
 .Bl -tag -width indent
-.It Fl a
-List all the currently available string or integer values.
 .It Fl A
-List all the known MIB names including opaques.
-Those with string or integer values will be printed as with the
+Equivalent to
+.Fl o
 .Fl a
-flag; for the opaque values,
-information about the format and the length is printed in addition the first
-few bytes is dumped in hex.
-.It Fl X 
-Same as
-.Fl A
-except the entire value of opaque variables is hexdumped.
+(for compatibility).
+.It Fl a
+List all the currently available non-opaque values.
+This option is ignored if one or more variable names are specified on
+the command line.
 .It Fl N
 Show only variable names, not their values.
+This is particularly useful with shells that offer programmable
+completion.
+To enable completion of variable names in
+.Nm zsh ,
+use the following code:
+.Bd -literal -offset indent -compact
+listsysctls () { set -A reply $(sysctl -AN ${1%.*}) }
+compctl -K listsysctls sysctl
+.Ed
 .It Fl n
-Specify that the printing of the field name should be
-suppressed and that only its value should be output.
-This flag is useful for setting shell variables.
-For example, to save the pagesize in variable psize, use:
+Show only variable values, not their names.
+This option is useful for setting shell variables.
+For instance, to save the pagesize in variable psize, use:
 .Bd -literal -offset indent -compact
 set psize=`sysctl -n hw.pagesize`
 .Ed
 .It Fl b
-Force the value of the variable(s) to be output in raw, binary
-format.  No names are printed and no terminating newlines are output.
+Force the value of the variable(s) to be output in raw, binary format.
+No names are printed and no terminating newlines are output.
 This is mostly useful with a single variable.
-.It Fl w Xo
-.Ar name Ns = Ns Ar value ...
-.Xc
-Set the MIB
-.Ar name
-to the new
-.Ar value .
-If just a MIB style
-.Ar name
-is given,
-the corresponding value is retrieved.
+.Fl o
+Show opaque variables (which are normally suppressed).
+The format and length are printed, as well as a hex dump of the first
+sixteen bytes of the value.
+.It Fl X
+Equivalent to
+.Fl x
+.Fl a
+(for compatibility).
+.It Fl x
+As
+.Fl o ,
+but prints a hex dump of the entire value instead of just the first
+few bytes.
 .El
 .Pp
 The information available from
diff --git a/sbin/sysctl/sysctl.c b/sbin/sysctl/sysctl.c
index 10850fe..68843c2 100644
--- a/sbin/sysctl/sysctl.c
+++ b/sbin/sysctl/sysctl.c
@@ -58,7 +58,7 @@ static const char rcsid[] =
 #include <string.h>
 #include <unistd.h>
 
-static int	Aflag, aflag, bflag, Nflag, nflag, wflag, Xflag;
+static int	aflag, bflag, Nflag, nflag, oflag, xflag;
 
 static int	oidfmt(int *, int, char *, u_int *);
 static void	parse(char *);
@@ -70,12 +70,9 @@ static void
 usage(void)
 {
 
-	(void)fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n",
-		"usage: sysctl [-bNn] variable ...",
-		"       sysctl [-bNn] -w variable=value ...",
-		"       sysctl [-bNn] -a",
-		"       sysctl [-bNn] -A",
-		"       sysctl [-bNn] -X");
+	(void)fprintf(stderr, "%s\n%s\n",
+	    "usage: sysctl [-bNnox] variable[=value] ...",
+	    "       sysctl [-bNnox] -a");
 	exit(1);
 }
 
@@ -86,10 +83,11 @@ main(int argc, char **argv)
 	setbuf(stdout,0);
 	setbuf(stderr,0);
 
-	while ((ch = getopt(argc, argv, "AabNnwX")) != -1) {
+	while ((ch = getopt(argc, argv, "AabNnowxX")) != -1) {
 		switch (ch) {
 		case 'A':
-			Aflag = 1;
+			/* compatibility */
+			aflag = oflag = 1;
 			break;
 		case 'a':
 			aflag = 1;
@@ -103,11 +101,19 @@ main(int argc, char **argv)
 		case 'n':
 			nflag = 1;
 			break;
+		case 'o':
+			oflag = 1;
+			break;
 		case 'w':
-			wflag = 1;
+			/* compatibility */
+			/* ignored */
 			break;
 		case 'X':
-			Xflag = Aflag = 1;
+			/* compatibility */
+			aflag = xflag = 1;
+			break;
+		case 'x':
+			xflag = 1;
 			break;
 		default:
 			usage();
@@ -116,10 +122,10 @@ main(int argc, char **argv)
 	argc -= optind;
 	argv += optind;
 
-	if ((wflag && (Aflag || aflag)) || (Nflag && nflag))
+	if (Nflag && nflag)
 		usage();
-	if (Aflag || aflag)
-		exit (sysctl_all(0, 0));
+	if (aflag && argc == 0)
+		exit(sysctl_all(0, 0));
 	if (argc == 0)
 		usage();
 	while (argc-- > 0)
@@ -146,17 +152,12 @@ parse(char *string)
 	bufp = buf;
 	snprintf(buf, BUFSIZ, "%s", string);
 	if ((cp = strchr(string, '=')) != NULL) {
-		if (!wflag)
-			errx(2, "must specify -w to set variables");
 		*strchr(buf, '=') = '\0';
 		*cp++ = '\0';
 		while (isspace(*cp))
 			cp++;
 		newval = cp;
 		newsize = strlen(cp);
-	} else {
-		if (wflag)
-			usage();
 	}
 	len = name2oid(bufp, mib);
 
@@ -166,7 +167,7 @@ parse(char *string)
 	if (oidfmt(mib, len, 0, &kind))
 		err(1, "couldn't find format of oid '%s'", bufp);
 
-	if (!wflag) {
+	if (newval == NULL) {
 		if ((kind & CTLTYPE) == CTLTYPE_NODE) {
 			sysctl_all(mib, len);
 		} else {
@@ -468,15 +469,17 @@ show_var(int *oid, int nlen)
 		}
 		/* FALL THROUGH */
 	default:
-		if (!Aflag)
+		if (!oflag && !xflag)
 			return (1);
 		if (!nflag)
 			printf("%s: ", name);
 		printf("Format:%s Length:%d Dump:0x", fmt, len);
 		while (len--) {
 			printf("%02x", *p++);
-			if (Xflag || p < val+16)
+			if (xflag || p < val+16)
 				continue;
+			if (len == 16)
+				break;
 			printf("...");
 			break;
 		}