Add support for a -q flag. While here make the custom argument parsing

use getopt instead of hacking on it more.  This change also fixes the
method of silencing the compiler warning about gfn being used
uninitialized.

Approved by:	cperciva
MFC after:	1 week

usr.sbin/chkgrp/chkgrp.8

@@ -34,6 +34,7 @@
 .Nd check the syntax of the group file
 .Sh SYNOPSIS
 .Nm
+.Op Fl q
 .Op Ar groupfile
 .Sh DESCRIPTION
 The
@@ -47,6 +48,12 @@ contains whitespace, and that the third field (the group ID) is
 numeric.
 It will also check for invalid characters in the group names
 and group members.
+The following options are available:
+.Bl -tag -width indent
+.It Fl q
+This option disables printing of text when the group format
+is correct.
+.El
 .Sh FILES
 .Bl -tag -width /etc/group -compact
 .It Pa /etc/group

usr.sbin/chkgrp/chkgrp.c

@@ -37,11 +37,12 @@ __FBSDID("$FreeBSD$");
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 #include <sysexits.h>
 
 static char empty[] = { 0 };
 
-static void
+static void __dead2
 usage(void)
 {
     fprintf(stderr, "usage: chkgrp [groupfile]\n");
@@ -53,24 +54,33 @@ main(int argc, char *argv[])
 {
     unsigned int i;
     size_t len;
+    int quiet;
+    int ch;
     int n = 0, k, e = 0;
     char *line, *f[4], *p;
     const char *cp, *gfn;
     FILE *gf;
 
-    /* check arguments */
-    switch (argc) {
-    case 1:
-	gfn = "/etc/group";
-	break;
-    case 2:
-	gfn = argv[1];
-	break;
-    default:
-	gfn = NULL; /* silence compiler */
-	usage();
+    quiet = 0;
+    while ((ch = getopt(argc, argv, "q")) != -1) {
+	    switch (ch) {
+		case 'q':
+			quiet = 1;
+			break;
+		case '?':
+		default:
+			printf("hello\n");
+			usage();
+	    }
     }
 
+    if (optind == argc)
+	    gfn = "/etc/group";
+    else if (optind == argc - 1)
+	    gfn = argv[optind];
+    else
+	    usage();
+
     /* open group file */
     if ((gf = fopen(gfn, "r")) == NULL)
 	err(EX_NOINPUT, "%s", gfn);
@@ -178,7 +188,7 @@ main(int argc, char *argv[])
 
     /* done */
     fclose(gf);
-    if (e == 0)
+    if (e == 0 && quiet == 0)
 	printf("%s is fine\n", gfn);
     exit(e ? EX_DATAERR : EX_OK);
 }