Use sudo only if needed

Now sudo will be only used if the user isn't in the group video.
In case of the use of sudo, a message will explain that.

1 files changed, 13 insertions, 1 deletions

diff --git a/light2.sh b/light2.sh
index 20e68a9..40b9410 100755
--- a/light2.sh
+++ b/light2.sh
@@ -12,10 +12,22 @@ else
     val="$1"
 fi
 
+right="sudo"
+for r in `groups`; do
+    if [ $r == "video" ] ; then
+        right=""
+    fi
+done
+
+
+if [ -n right ] ; then
+    echo 'To not use sudo, add yourself to the group "video"'
+fi
+
 if [ -n "$listBacklight" ] ; then
     for backlight in "$listBacklight"
     do
-        echo "${val}" | sudo tee "/sys/class/backlight/${backlight}/brightness" 2>&1 /dev/null
+        echo "${val}" | $right tee "/sys/class/backlight/${backlight}/brightness" 2>&1 /dev/null
     done
 else
     echo 'No backlight detected'