clean up code and add comments

brightness-by-daylight.sh

@@ -1,8 +1,8 @@
 #!/bin/sh
 
-# This is a script to set my external monitor's brightness
+# this is a script to set my external monitor's brightness
 # to high (70%) or low (40%) automatically according to day/night.
-# It uses ddcutil to access the monitor's settings and sunwait to know
+# it uses ddcutil to access the monitor's settings and sunwait to know
 # if it's day or night. It expects a file in the following format in
 # the .config directory (the values should be according to location)
 
@@ -13,14 +13,16 @@
 # high=70
 # low=40
 
-# Just run this script one manually to set it up to run perpetually (hopefully) using 'at'
+# just run this script one manually to set it up to run perpetually (hopefully) using 'at'
-# (Some distros don't come with 'at' preinstalled, so you might need to install 'at' and enable the 'atd' service.)
+# (some distros don't come with 'at' preinstalled, so you might need to install 'at' and enable the 'atd' service.)
 
-# It might also be a good idea to add '<location-of-this-script> scheduler' to your DE's autostart list, or to '.profile' so that it launches on system login
+# it might also be a good idea to add '<location-of-this-script> scheduler wait' to your DE's autostart list, or to '.profile' so that it launches on system login
-# (Sometimes I forget to turn on the monitor when I start my PC, so this is better than having a crontab)
+# (sometimes I forget to turn on the monitor when I start my PC, so this is better than having a crontab)
 
+# location of the config file
 confdir="/home/sintan/.config"
 
+# read from the config file
 if test -f $confdir/latlong.toml ; then
     source $confdir/latlong.toml
 else
@@ -28,19 +30,15 @@ else
     exit
 fi
 
+# get sun status
 sun_status=$(sunwait poll $latitude $longitude)
+[ $sun_status == "DAY" ] && target=$high || target=$low
 
-if [ $sun_status == "DAY" ]; then
+# do the brightness adjustment using ddcutil
-        target=$high
-    else
-        target=$low
-fi
-
 ddcutil setvcp 10 $target
 echo "Monitor brightness set to $target%, since it's $(echo $sun_status | tr '[:upper:]' '[:lower:]') time"
 
-# Check if we want to access the scheduler. If yes, create a schedule using `at`
+# check if we want to access the scheduler. If yes, create a schedule using `at`
-
 if [ "$1" == "scheduler" ]; then
     if [ $sun_status == "DAY" ]; then
         time_next=$(sunwait report 35.221050N 97.445938W | grep "Daylight:" | awk '{print $6}')
@@ -49,15 +47,16 @@ if [ "$1" == "scheduler" ]; then
     fi
     task_list=$(atq | grep $time_next | awk '{print $1}')
 
+    # loop through all `at` entries to see if a task already exists
+    flag=true
     for item in $task_list
     do
-        if ! [ $(at -c $item | sed 'x;$!d' | awk '{print $4}') == "$scriptdir/brightness-by-daylight.sh" ]; then
+        [ "$(at -c $item | sed 'x;$!d')" == "$scriptdir/brightness-by-daylight.sh scheduler wait" ] && flag=false
-            # we wait a minute so that the next schedule is set up properly (or sunwait reports day/night in a misleading way)
-            at -m $time_next <<< "sleep 60 && $scriptdir/brightness-by-daylight.sh scheduler"
-        fi
     done
 
-    if [ -z "$task_list" ]; then # in case there's no at entry
+    # sometimes we need to wait a minute so that the next schedule is set up properly (or sunwait reports day/night in a misleading way)
-        at -m $time_next <<< "sleep 60 && $scriptdir/brightness-by-daylight.sh scheduler"
+    [ "$2" == "wait" ] && sleep 60
-    fi
+
+    # actually create the schedule
+    $flag && at -m $time_next <<< "$scriptdir/brightness-by-daylight.sh scheduler wait"
 fi