So many of you, this is so basic that it's embarrassing. Any maybe to me too. But the truth is, I often forget the syntax. By mentioning it here, hopefully, I'll memorize it better.
To set a default environment variables, consider this example Bash program:
#!/bin/bash
: "${PORT:=8000}"
echo "Port number: $PORT"
When you run it, it defaults to the value 8000 (a string)
❯ bash dummy.sh
HOSTNAME:8000
And if you override the default:
❯ PORT=1234 bash dummy.sh
Port number: 1234
Note, you don't have to "define" the default on its own line. You can simplify it by defining the default where you use the environment variables. E.g:
#!/bin/bash
echo "Port number: ${PORT:=8000}"
This works the same.
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