sysctl: implement -q

function                                             old     new   delta
packed_usage                                       29208   29223     +15
sysctl_act_recursive                                 605     598      -7
sysctl_main                                          233     222     -11

Signed-off-by: Joshua Kahlenberg <jbkberg@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/procps/sysctl.c b/procps/sysctl.c
index 5296d0f..8786568 100644
--- a/procps/sysctl.c
+++ b/procps/sysctl.c
@@ -12,21 +12,23 @@
  */
 
 //usage:#define sysctl_trivial_usage
-//usage:       "[OPTIONS] [VALUE]..."
+//usage:       "[OPTIONS] [KEY[=VALUE]]..."
 //usage:#define sysctl_full_usage "\n\n"
-//usage:       "Configure kernel parameters at runtime\n"
-//usage:     "\n	-n	Don't print key names"
+//usage:       "Show/set kernel parameters\n"
 //usage:     "\n	-e	Don't warn about unknown keys"
-//usage:     "\n	-w	Change sysctl setting"
-//usage:     "\n	-p FILE	Load sysctl settings from FILE (default /etc/sysctl.conf)"
-//usage:     "\n	-a	Display all values"
-//usage:     "\n	-A	Display all values in table form"
+//usage:     "\n	-n	Don't show key names"
+//usage:     "\n	-a	Show all values"
+/* Same as -a, no need to show it */
+/* //usage:     "\n	-A	Show all values in table form" */
+//usage:     "\n	-w	Set values"
+//usage:     "\n	-p FILE	Set values from FILE (default /etc/sysctl.conf)"
+//usage:     "\n	-q      Set values silently"
 //usage:
 //usage:#define sysctl_example_usage
 //usage:       "sysctl [-n] [-e] variable...\n"
-//usage:       "sysctl [-n] [-e] -w variable=value...\n"
+//usage:       "sysctl [-n] [-e] [-q] -w variable=value...\n"
 //usage:       "sysctl [-n] [-e] -a\n"
-//usage:       "sysctl [-n] [-e] -p file	(default /etc/sysctl.conf)\n"
+//usage:       "sysctl [-n] [-e] [-q] -p file	(default /etc/sysctl.conf)\n"
 //usage:       "sysctl [-n] [-e] -A\n"
 
 #include "libbb.h"
@@ -37,9 +39,11 @@
 	FLAG_TABLE_FORMAT    = 1 << 2, /* not implemented */
 	FLAG_SHOW_ALL        = 1 << 3,
 	FLAG_PRELOAD_FILE    = 1 << 4,
+/* TODO: procps 3.2.8 seems to not require -w for KEY=VAL to work: */
 	FLAG_WRITE           = 1 << 5,
+	FLAG_QUIET           = 1 << 6,
 };
-#define OPTION_STR "neAapw"
+#define OPTION_STR "neAapwq"
 
 static void sysctl_dots_to_slashes(char *name)
 {
@@ -144,9 +148,11 @@
 //TODO: procps 3.2.7 writes "value\n", note trailing "\n"
 		xwrite_str(fd, value);
 		close(fd);
-		if (option_mask32 & FLAG_SHOW_KEYS)
-			printf("%s = ", outname);
-		puts(value);
+		if (!(option_mask32 & FLAG_QUIET)) {
+			if (option_mask32 & FLAG_SHOW_KEYS)
+				printf("%s = ", outname);
+			puts(value);
+		}
 	} else {
 		char c;