From 9e18b08b629c69e49417fd778fafc3f0217b4cc9 Mon Sep 17 00:00:00 2001
From: Erich Eckner <git@eckner.net>
Date: Fri, 21 Feb 2020 09:39:33 +0100
Subject: update-me: -c and -s new

---
 update-me.in | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/update-me.in b/update-me.in
index 46db7f7..903c30d 100644
--- a/update-me.in
+++ b/update-me.in
@@ -1,5 +1,40 @@
 #!/bin/bash
 
+usage() {
+  >&2 echo 'usage: update-me [-s|-c]'
+  >&2 echo '  -s: play it save'
+  >&2 echo '  -c: clear for exit'
+  exit $1
+}
+
+play_it_safe=false
+safety_file='/tmp/update-me.do-not-exit'
+
+case $# in
+  0)
+  ;;
+  1)
+    case "x$1" in
+      'x-s')
+        play_it_safe=true
+      ;;
+      'x-c')
+        if [ -f "${safety_file}" ] && kill -0 $(cat "${safety_file}"); then
+          rm "${safety_file}"
+          exit 0
+        fi
+        exit 1
+      ;;
+      *)
+        usage
+      ;;
+    esac
+  ;;
+  *)
+    usage 1
+  ;;
+esac
+
 preCmds=('hostname')
 cmds=()
 postCmds=('sync')
@@ -21,6 +56,18 @@ if command -v check-kernel >/dev/null; then
 fi
 
 exit_or_rescue_shell() {
+  if "${play_it_safe}"; then
+    printf '%s' "$$" >"${safety_file}"
+    >&2 printf '%s: waiting for clearance ...' "$(hostname)"
+    while [ -f "${safety_file}" ] && [ "$(cat "${safety_file}")" = "$$" ]; do
+      if read -t 1; then
+        >&2 printf ' rescue shell!\n'
+        bash
+        break
+      fi
+    done
+    >&2 printf ' clear.\n'
+  fi
   if [ "$1" -eq 0 ]; then
     >&2 printf '%s: Erfolg\n' "$(hostname)"
   else
-- 
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