From: Stefan Huber <shuber@sthu.org>
Date: Sun, 14 Jul 2019 10:20:15 +0000 (+0200)
Subject: ifonline: Check for default route
X-Git-Url: https://git.sthu.org/?p=shutils.git;a=commitdiff_plain;h=e7b2e754ab0f1198124536df89e468824e3ab001

ifonline: Check for default route
---

diff --git a/ifonline b/ifonline
index 5a26215..8bb8ae7 100755
--- a/ifonline
+++ b/ifonline
@@ -1,7 +1,13 @@
 #!/bin/sh
 
+set -e
+
 usage() {
-	cat << EOF
+  cat << EOF
+Executes a given command if there is an internet connection. Availability of an
+connection is tested by (i) the availability of a default route and (ii) the
+pingability of a test host.
+
 Usage:
  $0 [OPTIONS]
  $0 -h
@@ -9,31 +15,54 @@ Usage:
 
 OPTIONS:
   -h            Show this text
+  -v            Verbose output
+  -p HOST       Host for ping test. Default: 8.8.8.8
   -c CMD        Command to execute if online
 EOF
 }
 
 CMD=""
+VERBOSE=0
+PINGHOST="8.8.8.8"
 
-while getopts "hc:" OPTION; do
+while getopts "hvc:p:" OPTION; do
     
-	case "$OPTION" in
-		h)
-			usage
-			exit
-			;;
-		c)
-			CMD=$OPTARG
-			;;
-	esac
+  case "${OPTION}" in
+    h)
+      usage
+      exit
+      ;;
+    v)
+      VERBOSE=1
+      ;;
+    p)
+      PINGHOST=${OPTARG}
+      ;;
+    c)
+      CMD=${OPTARG}
+      ;;
+  esac
 done
 
-if [ -z "$CMD" ]; then
+if [ -z "${CMD}" ]; then
     echo "No command given."
     usage
     exit 2
 fi
 
-if ping -c1 8.8.8.8 2>&1 >/dev/null; then
-    $CMD
+if [ -z "$(ip r list exact default)" ]; then
+  if [ "1" -eq "${VERBOSE}" ];  then
+    echo "Not online because no default route."
+  fi
+  exit
+fi
+
+
+if ! ping -c1 "${PINGHOST}" 2>&1 >/dev/null; then
+  if [ "1" -eq "${VERBOSE}" ];  then
+    echo "Not online because cannot ping ${PINGHOST}."
+  fi
+  exit
 fi
+
+${CMD}