A little advanced mouse clicker in Bash for Linux

My today's goal was to create a little advanced mouse clicker in Bash for Linux powered by xdotool. This clicker implements 15 pixel random range in which it clicks for some users not wanting to get caught for some cheating. But that is not the idea. It is just part of it. It may have multiple uses.

There may be multiple issues. Although I tried hard over night to get "through" Bash. I am no question an expert on Bash, I am trying to learn Bash.

Further, this code is free to anyone.

Please address the potential issues.

```
#!/bin/bash

function random_number {

# we take two parameters: from and to, inclusive
# we return random number within this range

echo $[ $1 + $[ RANDOM % $2 ]]

}

function activate_window_via_name {

xdotool search --name "$1" windowactivate --sync

}

# we need to keep track of these two variables used by mouse_click function

previous_rand=10
operation_add=true

function mouse_click {

# 1. invert the operation_add boolean value;
# it seems Bash does not have inbuilt command for that
# 2. operation_add determines whether we will be adding or
# subtracting the random number later

if [[ $operation_add == true ]]; then

operation_add=false

else

operation_add=true

fi

# 2. generate random number between 0 and 7, inclusive;
# if the generated number is the same as the previous_rand,
# generate until it is different
# 2. rand will be later used as pixel offset from the given coordinates

rand=$(random_number 0 7)

while [[ $rand == $previous_rand ]]; do

rand=$(random_number 0 7)

done

# 3. we don't want to repeat clicks right with the same offset,
# so we store information about the previous_rand here

previous_rand=$rand

# WHAT IS THIS, WHY? probably was just temporary

pos_x=$1
pos_y=$2

# 4. depending on the boolean value of operation_add,
# we either add the rand, or subtract it to/from

Use $((...)) instead of $[...]

The $[...] syntax is obsolete. Use $((...)) instead.

Also, you don't need to use $ for variables within $((...)).
So instead of this:

echo $[ $1 + $[ RANDOM % $2 ]]

You can write like this:

echo $(($1 + RANDOM % $2))

Quote the right-hand side of == in [[ ... ]]

Instead of this:

while [[ $rand == $previous_rand ]]; do

Write like this, to prevent glob matching:

while [[ $rand == "$previous_rand" ]]; do

Remove unnecessary code

These lines are unnecessary and can be safely removed:

# WHAT IS THIS, WHY? probably was just temporary

pos_x=$1
pos_y=$2

Double-quote to prevent globbing and word splitting

In this call:

mouse_click     ${coords[$i]}   ${coords[$i + 1]}

You should double-quote both arguments to prevent globbing and word splitting.

Passing arrays to functions

The way you pass an array to mouse_click_coords is a bit unusual, and can be confusing. I think it will be cleaner and simpler to pass the values instead:

mouse_click_coords() {
    local coords=("$@")
    for ((i = 0; i < ${#coords[@]}; i += 2)); do
        mouse_click "${coords[$i]}" "${coords[$i + 1]}"
    done
}

function do_the_job_on_1920x1080 {
    local coords=(
        1000    500
        1000    500
        1000    500
        1000    500
        1000    500
    )

    mouse_click_coords "${coords[@]}"
}

Simplify do_some_mouse_clicking_job_until_ctrlc

Instead of getting the x and y resolutions separately with get_screen_resolution_x and get_screen_resolution_y,
it will be simpler to get them together:

do_some_mouse_clicking_job_until_ctrlc() {
    local resolution=$(xdpyinfo | awk '/dimensions:/ {print $2}')

    case "$resolution" in
        1920x1080) do_the_job_on_1920x1080 ;;
        3840x1080) do_the_job_on_3840x1080 ;;
    esac
}

StackExchange Code Review Q#130100, answer score: 6