I want the ability to pass a heredoc to the source command for local interpretation.
The body of the heredoc document will be injected later before calling the script, and can be multiline.
I came up with this trick, which works in zsh:
source <(<<'heredoc'
echo foo
sleep 10
echo done
heredoc
) && echo ok || echo no
it prints foo, sleeps 10 seconds, then prints done, then ok. So far, so good.
Now, the script needs to run in bash.
When I feed bash (or sh) the exact same thing, I only get ok, with no wait at all, as if the command I was providing with the heredoc was just true.
I cannot understand why, and how I can build the same behavior in bash and sh.
How to make it work in bash?
Remove any here documents and execute the commands. You could preserve the group.
{
echo foo
sleep 10
echo done
} && echo ok || echo no
You can use, both in zsh and bash, source /dev/stdin if you want to execute commands in the current execution environment coming from a steam, like a here document. No need for <( process substitution in either case. So here you go:
source /dev/stdin <<heredoc
echo foo
sleep 10
echo done
heredoc
Note: this looks very odd thing to do and most probably there are better solutions to what you are doing.
why
Because in bash empty redirection like a here document without a command does nothing. You have to for example cat the content of the stream created by here document to output it to standard output for process substation to capture it.