Finished project, everything working as expected

src/llight.sh

@@ -1,30 +1,108 @@
 #! /bin/bash
 
-echo "llight 1.0 2020"
+# main.sh
+# Josue Teodoro Moreira <jteodomo@gmail.com> <josue.moreira2@etec.sp.gov.br>
+# December 13, 2020
 
-target_folder=/sys/class/backlight/intel_backlight/
+target_folder=/sys/class/backlight/intel_backlight
 current_brightness=$(cat ${target_folder}/brightness)
 max_brightness=$(cat ${target_folder}/max_brightness)
 
-# functions
+# print usage / help
 usage()
 {
-    echo "$(basename $0) -[h | v | g | s | i | d]"
-    echo "  -h  shows this help and exit"
-    echo "  -v  shows version and exit"
-    echo "  -g  shows current brightness and exit"
-    echo "  -s  changes brightness by given value. Must be between 1 and ${max_brightness}"
-    echo "  -i  increases brightness by given value"
-    echo "  -d  decreases brightness by given value"
+    echo "$(basename $0) -[h | v | g | s | i | d]."
+    echo
+    echo "Make sure to run llight with administrator rights. e. g. 'sudo llight -h'."
+    echo
+    echo "  -h  shows this help and exit."
+    echo "  -v  shows version and exit."
+    echo "  -g  shows current brightness and exit."
+    echo "  -s  changes brightness by given value. Must be between 1 and 100."
+    echo "  -i  increases brightness by given value."
+    echo "  -d  decreases brightness by given value."
 
     exit 1
 }
 
-if [ $# -eq 0 ]; then
+set_by_value()
+{
+    if [ ${1} -lt 1 ] || [ ${1} -gt 100 ]; then
+        echo "Value must be between 1 and 100."
+
+        usage
+    fi
+
+    let new_brightness=$((${max_brightness} / 100 * ${1}))
+    echo "${new_brightness}" | sudo tee ${target_folder}/brightness > /dev/null
+}
+
+increase_by_value()
+{
+    if [ $((${current_brightness} + ${1})) -gt ${max_brightness} ]; then
+        echo "Already on maximum brightness. Try a smaller number or -s instead."
+
+        usage
+    fi
+
+    let new_brightness=$((${current_brightness} + ${1}))
+    echo "${new_brightness}" | sudo tee ${target_folder}/brightness > /dev/null
+}
+
+decrease_by_value()
+{
+    if [ $((${current_brightness} - ${1})) -lt 1 ]; then
+        echo "Already on minimum brightness. Try a smaller number or -s instead."
+
+        usage
+    fi
+
+    let new_brightness=$((${current_brightness} - ${1}))
+    echo "${new_brightness}" | sudo tee ${target_folder}/brightness > /dev/null
+}
+
+if [ $# -gt 2 ] || [ $# -eq 0 ]
+then
     usage
 fi
 
-# truncate -s 0 ${target_folder}/brightness
-# echo ${current_brightness} > ${target_folder}/brightness
+# get options
+options=":hvgsid"
+getopts ${options} args
+
+case ${args} in
+    h)
+        usage
+
+        ;;
+    v)
+        echo "llight 1.0"
+        echo "Developed by Josue Teodoro Moreira"
+
+        ;;
+    g)
+        echo ${current_brightness}
+
+        ;;
+    s)
+        set_by_value ${2}
+
+        ;;
+    i)
+        increase_by_value ${2}
+
+        ;;
+    d)
+        decrease_by_value ${2}
+
+        ;;
+    *)
+        echo "Invalid argument -${OPTARG}"
+        echo
+        usage
+
+        ;;
+esac
+
 
 exit 0