Detect os type and set JAVA_HOME

I would like to detect the os type in a bash script and set JAVA_HOME accordingly.

if   [[ $(type -t apt-get) == "file" ]]; then os="apt"
    elif [[ $(type -t yum)     == "file" ]]; then os="yum"
    else
            echo "Could not determine os."
    fi

case "$os" in

        apt)    pushd /etc/ \
                echo 'export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-amd64/' >> /etc/profile ;;

        yum)    pushd /etc/profile.d/ \
                echo 'export JAVA_HOME=/usr/lib/jvm/jre-1.7.0-openjdk.x86_64/' >> /etc/profile.d/user_env.sh ;;
esac

I have tried this but it seems to not be writing the export to the files.

Any help is greatly appreciated.

Solution

I'm not sure what purpose the pushd serves here, but you don't want the \ because that would be a continuation of the pushd command line and not actually run the echo command. You want, I think:

if   [[ $(type -t apt-get) == "file" ]]; then os="apt"
elif [[ $(type -t yum)     == "file" ]]; then os="yum"
else
    echo "Could not determine os."
fi

case "$os" in
        apt)    echo 'export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-amd64/' >> /etc/profile ;;
        yum)    echo 'export JAVA_HOME=/usr/lib/jvm/jre-1.7.0-openjdk.x86_64/' >> /etc/profile.d/user_env.sh ;;
esac

If you want to keep the pushd, it would be:

case "$os" in

        apt)    pushd /etc/
                echo 'export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-amd64/' >> /etc/profile ;;

        yum)    pushd /etc/profile.d/
                echo 'export JAVA_HOME=/usr/lib/jvm/jre-1.7.0-openjdk.x86_64/' >> /etc/profile.d/user_env.sh ;;
esac