reformat help output

[code/molly-guard.git] / shutdown

diff --git a/shutdown b/shutdown
index c7402018cd0effaa1012cb431d1cfa808d82b9ec..f12fde0fdb8ae5ca059af3d9318901a98bdede3f 100755 (executable)
--- a/shutdown
+++ b/shutdown
@@ -5,17 +5,16 @@
 # Copyright © martin f. krafft <madduck@madduck.net>
 # Released under the terms of the Artistic Licence 2.0
 #
-# $Id: shutdown 299 2006-10-16 14:40:47Z madduck $
-#
 set -eu
 
 ME=molly-guard
+CHECKSDIR=/etc/molly-guard/checks.d
 
 CMD="${0##*/}"
 EXEC="/sbin/$CMD"
 
 case "$CMD" in
-  halt|reboot|shutdown)
+  halt|reboot|shutdown|poweroff)
     if [ ! -f $EXEC ]; then
       echo "E: $ME: not a regular file: $EXEC" >&2
       exit 4
@@ -30,48 +29,87 @@ case "$CMD" in
     exit 1
     ;;
 esac
-ARGS="$@"
 
-do_real_cmd()
+usage()
 {
-  case "$ARGS" in
-    (*--molly-guard-do-nothing*)
-      ARGS0="${ARGS%%--molly-guard-do-nothing*}"
-      ARGS1="${ARGS##*--molly-guard-do-nothing}"
-      echo "$ME: would run: $EXEC ${ARGS0# } ${ARGS1# }"
-      exit 0;;
-    *) eval exec $EXEC "$ARGS";;
-  esac
-}
+  cat <<-_eousage
+       Usage: $ME [options]
+              (shielding $EXEC)
 
-# require $SSH_CONNECTION to be set, indicates an SSH session
-[ -n "${SSH_CONNECTION:-}" ] || do_real_cmd
-# require an interactive terminal connected to stdin
-test -t 0                    || do_real_cmd
-# pass through help commands
-case "$CMD $ARGS" in
-  (shutdown\ *-c*) do_real_cmd;;
-  (shutdown\ *-h*) do_real_cmd;;
-  (*--help*) do_real_cmd;;
-  *) :;;
-esac
+       Instead of invoking $EXEC directly, $ME will run a number of checks
+        to guard against accidental shutdowns/reboots.
 
-HOSTNAME="$(hostname)"
+        Some of the checks available are:
+        - Prompt the user for the machine's if the current shell is a child
+          of an SSH connection (or --pretend-ssh) has been given on the
+          command line, if the shell is connected to an interactive
+         terminal, and the actual command to execute is does not involve
+          --help or is \`shutdown -c'.
 
-sigh()
-{
-  echo "Good thing I asked; I won't $CMD $HOSTNAME ..."
-  exit 2
+         $ME will always interpose the prompt if the environment variable
+          ALWAYS_MOLLY is set to '1'.  This variable may be set in the file
+         /etc/default/${ME} .
+
+        - Print out a warning message with information about this host
+         before the action takes place.  You can use:
+               /etc/molly-guard.<Action>.message
+         To print out a message specific to the command you're trying to
+         use.  Or:
+               /etc/molly-guard.message
+         For a general warning message.
+
+       Only if the user satisfies all the checks will $ME take action.
+       Specifying --molly-guard-do-nothing as argument to the command will
+       make $ME echo the command it would execute rather than actually executing
+       it.
+
+       The actual command's help output follows:
+
+       _eousage
 }
 
-trap 'echo;sigh' 1 2 3 9 10 12 15
+ARGS=
+DO_NOTHING=0
+CHECK_ARGS=
+for arg in "$@"; do
+  case "$arg" in
+    (*-molly-guard-do-nothing) DO_NOTHING=1;;
+    (*-help)
+      usage 2>&1
+      eval $EXEC --help 2>&1
+      exit 0
+      ;;
+    (*-pretend-ssh) CHECK_ARGS="${CHECK_ARGS:+$CHECK_ARGS }--arg --pretend-ssh";;
+    *) ARGS="${ARGS:+$ARGS }$arg";;
+  esac
+done
 
-echo "$ME: SSH session detected!"
-echo -n "Please type in hostname of the machine to $CMD: "
-read HOSTNAME_USER || :
+do_real_cmd()
+{
+  if [ $DO_NOTHING -eq 1 ]; then
+    echo "$ME: would run: $EXEC $ARGS"
+    exit 0
+  else
+    eval exec $EXEC "$ARGS"
+  fi
+}
 
-[ "$HOSTNAME_USER" = "$HOSTNAME" ] || sigh
+if [ $DO_NOTHING -eq 1 ]; then
+  echo "I: demo mode; $ME will not do anything due to --molly-guard-do-nothing."
+fi
+
+# pass through certain commands
+case "$CMD $ARGS" in
+  (*shutdown\ *-c*) 
+    echo "I: executing $CMD $ARGS regardless of check results."
+    do_real_cmd
+    ;;
+esac
 
-trap - 1 2 3 9 10 12 15
+run-parts --exit-on-error --arg $CMD $CHECK_ARGS /etc/molly-guard/checks.d
 
-do_real_cmd
+# run-parts won't return to us if there are failures, but I'm paranoid.
+if [ $? == 0 ]; then
+  do_real_cmd
+  exit
+fi