cli: robustize abrt-console-notification.sh

- don't show any notifications without a terminal connected to stdout
- don't continue without writable $HOME directory
- forward all error messages to /dev/null

Resolves rhbz#1141485
Related to rhbz#1139001

Signed-off-by: Jakub Filak <jfilak@redhat.com>

src/cli/abrt-console-notification.sh

@@ -1,21 +1,39 @@
+# If shell is not connect to a terminal, exit immediately, because this script
+# should print out ABRT's status and it is senseless to continue without
+# terminal.
+tty -s || exit 0
+
+# If $HOME is not set, a non human user is logging in to shell but this script
+# should provide information to human users, therefore exiting immediately
+# without showing the notification.
+if [ -z "$HOME" ]; then
+    exit 0
+fi
+
+if [ -z "$ABRT_DEBUG_LOG" ]; then
+    ABRT_DEBUG_LOG="/dev/null"
+fi
+
 LPATHDIR="$HOME/.cache/abrt"
 SINCEFILE="$LPATHDIR/lastnotification"
 
 if [ ! -f "$LPATHDIR" ]; then
-    mkdir -p "$LPATHDIR"
+    # It might happen that user doesn't have write access on his home.
+    mkdir -p "$LPATHDIR" &> "$ABRT_DEBUG_LOG" || exit 0
 fi
 
-TMPPATH=`mktemp --tmpdir="$LPATHDIR" lastnotification.XXXXXXXX 2> /dev/null`
+TMPPATH=`mktemp --tmpdir="$LPATHDIR" lastnotification.XXXXXXXX 2> "$ABRT_DEBUG_LOG"`
 
 SINCE=0
 if [ -f "$SINCEFILE" ]; then
-    SINCE=`cat $SINCEFILE 2> /dev/null`
+    SINCE=`cat $SINCEFILE 2> "$ABRT_DEBUG_LOG"`
 fi
 
 # always update the lastnotification
 if [ -f "$TMPPATH" ]; then
-    date +%s > "$TMPPATH"
-    mv -f "$TMPPATH" "$SINCEFILE"
+    # Be quite in case of errors and don't scare users by strange error messages.
+    date +%s > "$TMPPATH" 2> "$ABRT_DEBUG_LOG"
+    mv -f "$TMPPATH" "$SINCEFILE" &> "$ABRT_DEBUG_LOG"
 fi
 
-abrt-cli status --since="$SINCE" 2> /dev/null
+abrt-cli status --since="$SINCE" 2> "$ABRT_DEBUG_LOG"