Add a vigr(8) utility which does for /etc/group what vipw(8) does for

/etc/master.passwd.

usr.sbin/Makefile

@@ -94,6 +94,7 @@ SUBDIR=	adduser \
 	trpt \
 	tzsetup \
 	ugidfw \
+	vigr \
 	vipw \
 	wake \
 	watch \

usr.sbin/vigr/Makefile

@@ -0,0 +1,6 @@
+# $FreeBSD$
+
+SCRIPTS=	vigr
+MAN=	vigr.8
+
+.include <bsd.prog.mk>

usr.sbin/vigr/vigr.8

@@ -0,0 +1,71 @@
+.\"-
+.\" Copyright (c) 2014 Dag-Erling Smørgrav
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd December 14, 2014
+.Dt VIGR 8
+.Os
+.Sh NAME
+.Nm vigr
+.Nd edit the group file
+.Sh SYNOPSIS
+.Nm
+.Op Fl d Ar directory
+.Sh DESCRIPTION
+The
+.Nm
+utility makes a temporary copy of the group file, allows the user to
+edit it, then verifies that the edited file is valid before installing
+it.
+.Pp
+The following options are available:
+.Bl -tag -width Fl
+.It Fl d Ar directory
+Edit the group file in the specified directory instead of the default
+.Pa /etc/group .
+.El
+.Sh ENVIRONMENT
+.Bl -tag -width EDITOR
+.It Ev EDITOR
+The editor to use instead of
+.Xr vi 1 .
+.It Ev TMPDIR
+The directory in which to store the temporary copy of the group file.
+.El
+.Sh SEE ALSO
+.Xr group 5 ,
+.Xr chkgrp 8 ,
+.Xr vipw 8
+.Sh HISTORY
+The
+.Nm
+utility appeared in
+.Fx 11.0 .
+.Sh AUTHORS
+The
+.Nm
+utility and this manual page were written by
+.An Dag-Erling Sm\(/orgrav Aq Mt des@FreeBSD.org .

usr.sbin/vigr/vigr.sh

@@ -0,0 +1,95 @@
+#!/bin/sh
+#-
+# Copyright (c) 2014 Dag-Erling Smørgrav
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+# $FreeBSD$
+#
+
+error() {
+	echo "$@" >&2
+	exit 1
+}
+
+usage() {
+	error "usage: vigr [-d dir]"
+}
+
+# Check arguments
+while getopts d: opt ; do
+	case $opt in
+	d)
+		etcdir="${OPTARG}"
+		;;
+	*)
+		usage
+		;;
+	esac
+done
+
+# Look for the current group file
+grpfile="${etcdir:-/etc}/group"
+if [ ! -f "${grpfile}" ] ; then
+	error "Missing group file"
+fi
+
+# Create a secure temporary working directory
+tmpdir=$(mktemp -d -t vigr)
+if [ -z "${tmpdir}" -o ! -d "${tmpdir}" ] ; then
+	error "Unable to create the temporary directory"
+fi
+tmpfile="${tmpdir}/group"
+
+# Clean up on exit
+trap "exit 1" INT
+trap "rm -rf '${tmpdir}'" EXIT
+set -e
+
+# Make a copy of the group file for the user to edit
+cp "${grpfile}" "${tmpfile}"
+
+while :; do
+	# Let the user edit the file
+	${EDITOR:-/usr/bin/vi} "${tmpfile}"
+
+	# If the result is valid, install it and exit
+	if chkgrp -q "${tmpfile}" ; then
+		install -b -m 0644 -C -S "${tmpfile}" "${grpfile}"
+		exit 0
+	fi
+
+	# If it is not, offer to re-edit
+	while :; do
+		echo -n "Re-edit the group file? "
+		read ans
+		case $ans in
+		[Yy]|[Yy][Ee][Ss])
+			break
+			;;
+		[Nn]|[Nn][Oo])
+			exit 1
+			;;
+		esac
+	done
+done