anticrash.sh

#!/bin/bash

# SCRIPT TO KILL PROCESSES IF MEMORY IS UNDER THRESHOLD
# USER SETTINGS: free_needed, max_lines
# licence: MIT, (c) 2025 luckydonald


# Declare an associative array for memory limits
declare -A free_needed free_needed_bytes

# Set memory limits for each application
free_needed["firefox"]="3GB"
free_needed["pycharm"]="1GB"

# How many messages to keep?
max_lines=10

# For the `.desktop` file install command, where to?
dot_desktop_install_dir="${HOME}/.local/share/applications"
dot_desktop_install_name="anticrash.desktop"
dot_desktop_autostart_dir="${HOME}/.config/autostart"

# Convert the memory limits to bytes
for app in "${!free_needed[@]}"; do
    free_needed_bytes[$app]=$(echo "${free_needed[$app]%B}" | numfmt --from=iec --to=none)
    echo "Kill ${app} if RAM below ${free_needed[$app]} (${free_needed_bytes[$app]})"
done


declare -a messages

function printer {
    # Add the new message to the array
    txt="$(date +"%Y-%m-%d %H:%M:%S") | $1"
    messages+=("${txt}")

    # Print the messages
    # If we have less than max_lines, just print normally
    if [ ${#messages[@]} -le $max_lines ]; then
        echo "${txt}"
    else
        messages=("${messages[@]:1}")  # Shift the array to remove the oldest message
        # Move the cursor up to the start of the message area
        tput cuu $max_lines  # Move cursor up by max_lines
        tput el              # Clear the line

        # Print the messages
        for msg in "${messages[@]}"; do
            echo "$msg"
        done

        # Move the cursor to the next line after printing
        tput cud 1          # Move cursor down by 1
    fi
}

function do_check {
	free_txt=$(cat /proc/meminfo | grep MemAvailable: | awk '{print $2 toupper($3)}')
	free=$(echo "${free_txt}" | numfmt --from=iec --to=iec-i --suffix=B)
	free_num=$(echo "${free_txt%B}" | numfmt --from=iec --to=none)
	printer "Currently free: ${free} (${free_num})"
	
	# Check memory for each application
	for app in "${!free_needed[@]}"; do
		if (( free_num < free_needed_bytes[$app] )); then
            echo ""
			echo "Not enough memory for ${app}. Killing it."
			echo "Kill it with faia"
			killall "$app"
		fi
	done

}




# Ask the user if they want to run the script once or forever
while true; do
    # Determine if the script is not being run in a TTY (interactive)
    if [ ! -t 1 ]; then
        choice="once"
    elif [[ "$1" == ".desktop" ]]; then
        choice="forever"
    else
        echo ""
        echo ""
        echo "Do you want to run the memory check once or forever?"
        echo "Please enter 'once' or 'forever' for running the program."
        echo "Please enter 'install' or 'uninstall' for writing a run configuration to the system's autostart, or removing it."
        read -p "(once/[forever]/install/uninstall): " choice
        if [[ -z "$choice" ]]; then
            choice="forever"
        fi
    fi
    case "$choice" in
        once)
            do_check
            break
            ;;
        forever)
            while true; do
                do_check
                sleep 1  # Wait for 10 seconds before the next check
            done
            ;;
        install)
            mkdir -p "${dot_desktop_install_dir}"
            dot_desktop_install_location="${dot_desktop_install_dir}/${dot_desktop_install_name}"
            dot_desktop_autostart_location="${dot_desktop_autostart_dir}/${dot_desktop_install_name}"
            dot_desktop_home_location="${HOME}/${dot_desktop_install_name}"
            echo '#!/usr/bin/env xdg-open' > ${dot_desktop_home_location}
            echo '[Desktop Entry]' >> ${dot_desktop_home_location}
            echo 'Version=1.0' >> ${dot_desktop_home_location}
            echo 'Type=Application' >> ${dot_desktop_home_location}
            echo 'Name=AntiCrash' >> ${dot_desktop_home_location}
            echo 'Comment=Run the anti-crash script' >> ${dot_desktop_home_location}
            echo "Path=$HOME" >> ${dot_desktop_home_location}
            echo "Exec=$HOME/anticrash.sh .desktop" >> ${dot_desktop_home_location}
            echo 'Icon=utilities-terminal' >> ${dot_desktop_home_location}
            echo 'Terminal=true' >> ${dot_desktop_home_location}
            echo 'Categories=Utility;' >> ${dot_desktop_home_location}
            echo "File written to ${dot_desktop_home_location}."
            chmod +x ${dot_desktop_home_location}
            desktop-file-install --dir="${dot_desktop_install_dir}" "${dot_desktop_home_location}"
            echo "File installed to ${dot_desktop_install_location}."
            update-desktop-database "${dot_desktop_install_dir}"
            echo "Desktop Database updated."
            ln -s ${dot_desktop_install_location} "${dot_desktop_autostart_location}"
            
            chmod +x ${dot_desktop_autostart_location}
            echo "File symlinked to autostart at ${dot_desktop_autostart_dir}/${dot_desktop_install_name}"
            ;;
        uninstall)
            mkdir -p "${dot_desktop_install_dir}"
            dot_desktop_install_location="${dot_desktop_install_dir}/${dot_desktop_install_name}"
            dot_desktop_autostart_location="${dot_desktop_autostart_dir}/${dot_desktop_install_name}"
            rm "${dot_desktop_autostart_location}"
            echo "File symlink removed from autostart at ${dot_desktop_autostart_location}."
            rm "${dot_desktop_install_location}"
            echo "File removed from ${dot_desktop_install_location}."
            ;;
        *)
            echo "Invalid choice."
            ;;
    esac
done