Why read builtin command has different behaviour on zsh and bash?

Question

running following command on zsh

zsh$ echo Hello | read str ; echo "str is: "$str

str is: Hello

whereas in bash, it doesn't work

bash$ echo Hello | read str ; echo "str is: "$str
str is: 

This thread mentions read command runs in subshell so current session has no clue about it. I'm not able to find why it works in zsh.

Answer 1

The read command has the same behaviour in both shells, but bash runs the read in a subshell whereas zsh does not.

Some shells don't need to use a subshell for the read in your example (in general, the last command in a pipeline).

To avoid having to switch to another shell interpreter, you may have the read read from something other than a pipe:

read str <<<'hello'
printf 'str is %s\n' "$str"

Or, if all you want is to output the string, output it in the same subshell:

echo 'hello' | { read str && printf 'str is %s\n' "$str"; }