Can a shell script set environment variables of the calling shell? [duplicate]

Answer 1

I created a solution using pipes, eval and signal.

parent() {
    if [ -z "$G_EVAL_FD" ]; then
            die 1 "Rode primeiro parent_setup no processo pai"
    fi
    if [ $(ppid) = "$$" ]; then
            "$@"
    else
            kill -SIGUSR1 $$
            echo "$@">&$G_EVAL_FD
    fi
}
parent_setup() {
    G_EVAL_FD=99
    tempfile=$(mktemp -u)
    mkfifo "$tempfile"
    eval "exec $G_EVAL_FD<>'$tempfile'"
    rm -f "$tempfile"
    trap "read CMD <&$G_EVAL_FD; eval \"\$CMD\"" USR1
}
parent_setup #on parent shell context
( A=1 ); echo $A # prints nothing
( parent A=1 ); echo $A # prints 1

It might work with any command.