post_install() {
       # do something here
       post_upgrade
}
post_upgrade() {
       # do something here
       [[ -x /usr/bin/xdg-icon-resource ]] && xdg-icon-resource forceupdate --theme hicolor
       [[ -x /usr/bin/update-desktop-database ]] && update-desktop-database -q
       [[ -x /usr/bin/gtk-update-icon-cache ]] && gtk-update-icon-cache -f /usr/share/icons/hicolor
}
post_remove() {
       # do something here
       post_upgrade
}