if command; then
? ? echo notify user OK >&2
else
? ? echo notify user FAIL >&2
? ? return -1
fi

check() {
? ? local command=("$@")

? ? if "${command[@]}"; then
? ? ? ? echo notify user OK >&2
? ? else
? ? ? ? echo notify user FAIL >&2
? ? ? ? exit 1
? ? fi
}

check command1
check command2
check command3

installed () {
? ? ? ? command -v "$1" >/dev/null 2>&1
}
if installed 
then
? ? ? ? ?xx
else
? ? ? ?  ?xxx
?fi

command1 || exit
command2 || exit
command3 || exit

$ ?bash -e xx.sh
#!/bin/bash -e xx.sh
command1
command2
command3

$ bash xx.sh?
#!/bin/bash
set -e?
command1
command2
command3

if do some command; then
? ? echo notify user OK
else
? ? echo notify user fail
? ? exit 255 ?# exit code must be unsigned short
fi

do some command
if [ $? -eq 0 ]; then
? ? echo notify user OK
else
? ? echo notify user FAIL
? ? return -1
fi

die() {
? ? local message=$1

? ? echo "$message" >&2
? ? exit 1
}

command1 || die 'command1 failed'
command2 || die 'command2 failed'
command3 || die 'command3 failed'

warn () {
? echo "$@" >&2
}

die () {
? status="$1"
? shift
? warn "$@"
? exit "$status"
}

do some command && echo notify user OK || die 255 Notify user fail