Install and deistall using .sh scripts

Hello everyone. I'm testing installation and deinstallation of software. I'm using .sh scripts. My script on Sikulix is below.
How I can get signal from sh.script, that it is executed without errors? How I use wait("install_success.png"). Maybe exist other way. Thanks for help.

click("start.png")
click("util.png")
click("fly-term.png")
sleep(2)
type("sudo su" + Key.ENTER)
sleep(2)
type("mc" + Key.ENTER)
sleep(2)
type("cd /root" + Key.ENTER)
sleep(3)
doubleClick("iso.png")
sleep(3)
type(Key.ALT + Key.SHIFT + "+")
type("*" + Key.ENTER)
sleep(3)
type(Key.TAB)
type("cd /root/repo" + Key.ENTER)
type("rm -rf /root/repo/*" + Key.ENTER)
sleep(3)
type(Key.TAB)
click("copy.png")
sleep(3)
click("next.png")
sleep(35)
type(Key.TAB)
type("chmod +x ./install-server.sh" + Key.ENTER)
sleep(5)
type("./install-server.sh" + Key.ENTER)
sleep(70)
type(Key.PAGE_DOWN + Key.ENTER)
sleep(180)
type("o",KEY_CTRL)
wait("install_success.png")
sleep(2)
type("o",KEY_CTRL)
type("chmod +x ./install-arm.sh" + Key.ENTER)
sleep(3)
type("./install-arm.sh" + Key.ENTER)
sleep(60)
type("o",KEY_CTRL)
wait("install_success.png")
App.close("fly-term")