Check list of hosts for hostname and run if app isn't installed

Question

Having some issues checking whether the hostname of the current host matches a whitelist and running an if statement that only runs if the host matches the whitelist and an application is installed. Here's what I have.. where am I going wrong? It's always returning exit 1 no matter what.

#!/bin/bash

WHITELIST=(host1 host2 host3)

printf -- '%s\n' "${WHITELIST[@]}" | grep $HOSTNAME

if [ -e "/Applications/myapp.app" ] && [ $? = 1 ];
then
    echo "myapp exists and hostname doesn't match whitelist"
    exit 0
else
    echo "myapp doesn't exist or hostname matches whitelist"
    exit 1
fi

Answer 1

The immediate problem is that $? is the result of [ -e "/Applications/myapp.app" ]. You'll want to avoid the antipattern anyway; see Why is testing “$?” to see if a command succeeded or not, an anti-pattern?

I'm guessing you also want to avoid using the host name as a regular expression for grep (add -F), or check whether it's a substring of anything on the whitelist (add -x to match whole lines only).

Tangentially, avoid upper case for your private variables.

#!/bin/bash

whitelist=(host1 host2 host3)

if [ -e "/Applications/myapp.app" ] &&
    ! printf -- '%s\n' "${whitelist[@]}" | grep -xF "$hostname"
then
    echo "myapp exists and hostname doesn't match whitelist"
    exit 0
else
    echo "myapp doesn't exist or hostname matches whitelist"
    exit 1
fi

The -- in printf isn't strictly necessary, since you are in complete control over the format string, and it doesn't start with a dash.

Ideally, you'd probably want to avoid using an external process (grep) for anything the shell can handle natively; see also Check if a variable exists in a list in Bash