Pass variable from a child to parent in KSH

Question

I have to work with KSH (yeah that hell shell). I need to use a fork, a subroutine as following:

    #!/bin/ksh

    PIPE=PIPE_$$
    PIPE_ERR=PIPE_ERR_$$

    export TEST_FILS

    $(. ./LanceFils.ksh 2>${PIPE_ERR} 1>${PIPE}) &
    PID_CHILD=$!
    echo "Nom du fichier PIPE: ${PIPE}"
    echo "Processus fils : " $!
    wait ${PID_CHILD}

    echo "Code retour: " $?
    echo "Sortie standard de PROC_FILS : " $(cat ${PIPE})
    echo "Sortie d'erreur(s) de PROC_FILS : " $(cat ${PIPE_ERR})

    echo "Contenu de TEST_FILS: ${TEST_FILS}"
    rm -rf ${PIPE}

Content of LanceFils.ksh

    #!/bin/ksh

    TIMEOUT=5

    export TEST_FILS

    echo "Je suis le script fils et j'attends ${TIMEOUT} secondes" 
    echo "Nom du pipe du pere ${PIPE}"
    sleep ${TIMEOUT}

    TEST_FILS="Je suis le fils"
    echo "Salut c'était bien !!!"
    exit 10

I know this do not work, btw i try to find a way to make it works ... In my code you can see i want share TEST_FILS variable between child and parent. There is way in KSH to share a variable, as in perl by using "share" or if i have to use a pipe like in C ?

Thank you.

Answer 1

Variables can be passed from a parent shell to child shell, not the other way around. However, you can do a workaround if you are really in need of the value set in the child shell.

One possible workaround: In the child shell, write the env variables of your interest along with their values to a file. Once you are back in the parent shell, run this file so that the env variables needed are overwritten with what is set in the file. You can refer here for an example.