Bash script to install it self as systemd timer

systemd-timer-install.sh

#!/usr/bin/env bash

# set -x

script_name=$(basename "${0%.*}")

install_systemd_timer() {
    if [ -z "$1" ]; then 
        echo "Timer interval not defined"
        return 1
    fi
    if [ "$1" -ge 0 ] && [ "$1" -le 60 ]; then
        echo "Install systemd timer..."
    else
        echo "Timer minutes interval is out of range 1 .. 59"
        return 1
    fi
    echo "Install /etc/systemd/system/$script_name.timer"
cat << _EOF_ > /etc/systemd/system/$script_name.timer

[Unit]
Description=$script_name every $1 minutes

[Timer]
OnBootSec=1min
OnCalendar=*:0/$1

[Install]
WantedBy=basic.target

_EOF_
echo "Install /etc/systemd/system/$script_name.service"
cat << _EOF_ > /etc/systemd/system/$script_name.service

[Unit]
Description=$script_name oneshot service

[Service]
Type=oneshot
User=root
Group=root
ExecStart=$(realpath $0)
LogLevelMax=err
# emerg , alert, crit, err, warning, notice, info, debug
_EOF_
        systemctl daemon-reload
        systemctl enable $script_name.timer
        systemctl start  $script_name.timer
        systemctl status  $script_name.timer
}

if [ "$1" = "install" ];then
    if install_systemd_timer $2; then
        exit 0
    else
        exit $?
    fi
fi

# script to run ...