shell脚本如何知道它在Solaris区域中运行？

if [ "$(uname)" = "SunOS" ]; then
    echo "This script is running on Solaris"
fi

if [ "$(/usr/bin/uname)" = "SunOS" ]; then
    echo "This script is running on Solaris"
fi

os=$(uname)
if [ "$os" = "SunOS" ]; then
    echo "This script is running on Solaris"
fi

if [ "$OSTYPE" = "sunos" ]; then
    echo "This script is running on Solaris"
fi